Undertale is a role-playing video game created by American indie developer and composer Toby Fox. In the game, players control a human child who has fallen into the Underground, a large, secluded region underneath the surface of the Earth, separated by a magic barrier and populated by the monster race. The player goes on a quest to reach the surface, and meets various monsters along the way.

While there is a lot of depth to undertale, much of it is not able to be expressed in words directly due to much of it resting in the particular way and compelling nature in which it conveys the wide variety of emotional tones contained therein. This range is highly wide, managing to have compelling parts with strong tones of almost every type of emotional range. Many of which are considered to compel these in much stronger ways than most media.

Deltarune is the sequel to undertale which continues the narriative but in an alternate universe and which focuses on different themes. As of yet only the first chapter has been released. Differing from undertale, deltarune has you control an entire party of people rather than onle one. The player controls a human, Kris, in a world where monsters live on the surface of the Earth. Kris and a classmate named Susie fall from Earth into a place called the “Dark World” where they meet Ralsei, who informs them that they are heroes destined to restore balance to the world. The players meet various beings who call themselves "Darkners" during a prophesied quest to seal the dark fountain.

Undertale has many inspirations, but megaten games are actually one of the main inspirations. Toby fox mentions how he was inspired by the fact that in megaten games, you get into not battles, but encounters, and that these encounters can be ended without violence via communication. Various other aspects may also be inspired by it, such as the graphics for the last fight on the pacifist route being a potential reference to strange journey. This page will not be about comparing undertale with megaten however, but merely addressing its own ideas.

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Undertale

Choice

One of the major themes of undertale that many of the others rest on is the nature of choice. The setup of the game highlights the fact that many things are in fact choices that people might ordinarily not really think of as a choice. It highlights this theme by using the mechanics of rpgs against the player by offering the option to not kill enemies that people might not be used to in this type of game, offering options that they might not have expected for the setting. And this ties in with both the theme and narrative of the game itself by having the endings vary due to these choices and tying the concept to real world applications, to highlight that many things people may feel pulled along with are actually options they are making, consciously or not.

The game then uses this to highlight the reality that one can make better choices than the ones that they might feel pulled along to do, which are represented by the neutral route of the game. With the good route showing something that requires taking a step back and deviating from what one might feel as the primary pull. This ties to the next idea of preconceived notions.

Preconceived notions

One of the major themes of undertale is the idea of preconceived notions, and the realization when you step back that many of them are not actually correct. The narrative of the game itself is structured to use your preconceived notions against you, both in terms of how the game reacts to you playing it like a standard rpg, as well as working to catch you off guard such as being aware when you reload or reset saves, something that many people would not be expecting.

This presentation can be hard hitting, since it makes a big show of being aware of what many of your preconceived notions are going to be, and showing you why they do not apply. Something that if it can apply so simply here is something you need to take into consideration when applying similar ones to any topic. The game uses your preconceived notions against you, and in many ways is structured to let you know that it will always be a step ahead, being aware of how you are going to approach given situations. It shows that the ones you come in with are often in error in this situation, which is a straightforward emphasis on that preconcieved notions in general are something you may need to step back and take a deeper look at, especially when there can be large consequences to how you use them. That certain paradigms of action you think are reasonable may in fact have issues with them.

This narrative about the effects of preconceived notions is worked into the story as well. Including in both a straightforward and in a meta sense. The story itself presents you as a lost person in dangerous territory, and as such depicts you fighting back as a reasonable situation. But it reveals over time that not only is some of that not accurate, since in many cases you were the one preemptively attacking, but in the meta sense you as a player being counted as part of the story are in no danger, and as such there is awareness that the risk involved with avoiding danger does not apply to you.

In the game's world this of course applies between humans and monsters and how they view eachother as well. You see the monster's perspective, and how they see humans, filled with hate, and thinking humans deserve death. But the other perspective is implicitly shown as well, more subtly. Asgore, the king of monsters is shown with a subtly demonic aesthetic. He has a red trident, horns, lives underground, etc. The implication of this being that human stories of demons could be an actual demonization of the stories of what monsters are like. Ones that got warped and more removed from reality over generations. These preconceived notions about outsiders and breaking free from them being a major theme also. One that could also veer into being a religious statement, showing that what one demonizes works its way into the religious paradigm as well.

Likewise, the binary of nice vs scary is also inverted. You are shown the contrast between humans and monsters, with monsters being presented as scary only for this as a whole to be turned on its head. And in the narrative of the game itself, it begins with flowey being presented as a harmless friendly character who will be helpful, only to be inverted, then the flow of the story itself presents asgore as scary and dangerous only for it to be shown that he himself is a relatively nice person who feels intense guilt over what he has done, and feels it comes from necessity. At the same time, this inversion is not absolute and shows nuance, since many characters will still have degrees of danger to them. Asgore when you meet him gives you every opportunity to leave and to avoid fighting him, but is willing to kill you if you don't relent, despite the agony it gives him, and the show of how little his heart is still in the idea of doing so.

This also shows how your perspectives can be shaped by prior events. After being saved from flowey by toriel, it likewise often sets the tone for thinking that she might want to harm you as well. After being betrayed the first time, it might make you spend much more time asking the question of who following this is going to betray you as well even after they are established as someone unlikely to do so. The interrelation between trust and mistrust is woven over the course of the events at large, with the situation calling to mind your need to ask it about various people in such a situation. The various characters all have their own reasons for responding to you in the ways they do, but you as an initial stranger cannot know them. This can go both directions, either for a better or worse angle. Toriel not only doesn't try to harm you, but will even go to her own death, deliberately avoiding doing so to protect you, deliberately missing you if you end up falling in to fighting her for real.

The themes of demonization could also apply to social demons. The game shows homosexual relationships in a positive light, alongside other similar issues like mettaton being a ghost who felt trapped in his (ironically) lack of skin, and identified with a new body. Interestingly, inside the universe of this, these are not presented as in your face, or something that the acceptance of is in question, but as outright normal things, ones that only exist to be positive normalizing depictions. Something that people still say that media in general often fails to accomplish.

Real life

One of the ultimate points of the meta aspect of the game is to let you know that the themes are contextually meant to apply to real life, rather than just the context of the game world. Ultimately, you are playing as yourself, the player in undertale, despite there being two in-game people you have control over. And this changes some of the connotations of the events. For instance, at the end of the first route, on neutral, sans has a message directly meant to be for you the player rather than the character. The message being how if someone is in no danger over the course of the events, it implies they have a higher level of responsibility to not harm people. The only reason they wouldn't is if they didn't care or want to go through the inconvenience of finding out how to do so. Because they don't see the people as mattering enough.

This has a double aspect of course. The immediate reason you might not care and wouldn't go out of your way to save everyone is because it is literally a game. The characters aren't real, and so it doesn't strictly speaking matter what happens to them. But this meta aspect applies to the game itself. Within its world, by the world's rules they are real beings, which implies that from their perspective, being aware of the ability to reset time as you have, all they know is that they are at the mercy of something that they can't control. Something they call the anomaly.

This fact of you being in no danger presented as a reason for why you should take a higher path carries over to real life. Since it is being addressed at you specifically, the real life analogue is the realization that you as a person are generally not in lethal danger most of the time. Day to day, you do actually have the opportunity to take a higher path. And for many people, the reason they do not ultimately amounts to, similar as in the game, inconvenience or other issues. Since this ties to the previous theme of preconcieved notions, it is calling you to turn on your head the idea that you don't need to step back and think over how you do things. To realize that in many ways, you might not be doing things the optimal way, and the realization that you can in fact do much better. To some, they are not aware that a higher path even exists for day to day events, or hadn't considered the presence of one.

That is also why the routes in undertale are not really morally gray, but are strictly good, neutral, and evil. It is not a game necessarily that much about ideology per say, although it does have ideological aspects as well. It is about goodness in general, moral motivation, and the call to step back to realize what your relationship to it is, and how that can be improved. Here, the distinction is shown by the fact that the neutral ending is something presented first as reasonable from the perspective of you as a lost person in a strange place, only to show the steps along which it was less so than it seemed.

Another interesting thing the meta aspect shows is both that there are some events you have the power to change at any time, as well as the fact that there are some you do not. There are certain things that you really will reach a point at which you cannot go back, and can never change the outcome for. As the game shows how if you take the genocide ending it implies that chara now irrevocably has power over the game world forever. But at the same time, there are certain trends that to stop and self reflect can change the course of. Which also leads to the interesting point of how the good route can be played after neutral, with it treating it like a continuing story. Since it is using the cyclical nature of the repeat plot to show the idea of day to day events that repeat, but that you can set a different course through.

This focus on reality applies to many of the characters themselves in terms of their differing roles in the plot. Many of them at first seem underdeveloped as if their role in the story is only as a token presence without much in the way of depth to it. But over time, especially in the good path it expands on this. Many of them are flawed characters, and some of this is implied never to be resolved. Which is shown in the end with how toriel still doesn't get back together with asgore. But that is on purpose too. They aren't designed to be perfect. And your interactions with them don't have an archetypical quality. Merely the feeling of a journey and getting to spend some time with them for awhile. And in the process learn about the reality of different people who have their own unique lives. Such as with papyrus, who is the only character in the game who won't kill you no matter what, even on accident. There is no gameplay reason for including this. But its to show that he is his own person, and what makes him unique from all others.

Evil

Another aspect of what the game shows about good and evil is the fact that evil in the sense people normally think of it tends to not really be a common thing. And this is highlighted in the difference between the neutral and evil routes, as well as between many of the characters. Namely, that while people who are truly evil or for lack of using the term outright willing to hurt others with no inhibitions whatsoever do exist, that most bad things that happen most of the time do not actually come from people like this. People to that extreme are few and far between, and in many cases, the day to day problems we go through come from the actions not of the pure evil, but from people who are otherwise loosely within the bounds of neutrality.

This is exemplified in a few ways. The game shows you various characters such as undyne who might not be the nicest people, and are willing to kill humans out of the idea that humans are bad, but who are presented somewhat sympathetically, and who from their own perspective are not an outright uncaring person. Undyne ultimately considered their situation a state of war, and her antagonism against humans to be something humans were the ultimate aggressors in, and antagonism against them as a necessary process to fix the problems of monsters. For instance, on the evil route, realizing that humans and monsters have a common enemy, her antagonism against them erodes rather quickly, coming with a likely realization of needing to unite after all, and the possibility of doing so.

Likewise, the entire thing with the neutral ending shows that from your perspective what you did seemed reasonable. In fact, sans doesn't even judge you much unless the amount you killed was extraordinarily high. This goes to show that a lot of bad things are caused day to day by people who don't really openly go down the route of pure apathy and sociopathy. That its just something that stems from your normal interactions, as well as some of the preconceived notions that underlie them. This is the ultimate thing being shown with these neutral routes and characters. That most problems come not from the outright evil, but from the ordinary day to day interactions of people who in their own first person perspective have reasons to be sympathetic to much of them. Some bad things even come from people who are well intentioned, or who otherwise aren't aware that what they are doing will end badly.

This sympathy of course does not mean that their actions are correct or don't need to be changed. Rather, it is a call to step back and take a look at societal problems or even individual in general, realizing that many of them stem from legitimate misunderstandings or being at odds for various reasons, or generalized apathy of people who all around are not trying to be deliberately malevolent. On the one hand it is about sympathy, but on the other it is about realizing that you too are part of this, and can look at what situations you can do better in. It goes back to the realization that in day to day situations in which you are in no danger, there is often a higher path to take.

Despite this, it is not denying that outright malevolence exists. But one thing it does show is the emptiness of these paths. That oftentimes they can lead to outright self destruction, and lead to, or maybe even came from an empty inside. One that even the darkness won't come to fill. However, even in the case of people it depicts as more actively malevolent, it is not necessarily implying a state of unshakable evil. In flowey's case, he is driven insane from depression and feelings of isolation. Him giving a meta talk about how he sees people as props, which makes it hard to care about them.

This idea of seeing people as props overlaps with the themes of depression (described below) in which your lack of connection with others can cause you to not see them in an empathetic way. Here this is described as one underlying cause behind even larger malevolence. Since he did not start as an evil being, but over time got demoralized. While it leaves more ambiguous the reasons for chara / or you the player to take these actions, for flowey it goes back to the idea of being caught in a cycle. This is a metaphor for day to day living in a state of depression and isolation, the idea that everything is empty and nothing changes, and so over time you come to think that nothing matters. A fatalistic idea that your actions have no meaning, and so you can undergo motive decay making you care less about others. None of this is to say that the game is implying that being depressed itself can make you turn sociopathic. Though there are lonely people for whom the isolation and depression has a large hand in it. But it shows that even for some of the worst people, there are some for whom others could still help them. (Though notably this applies to flowey / asriel, but is not applied to chara, who no path can lead to the redemption of).

In terms of seeing the characters as props, this obviously ties to the meta fact that for you as a player, the game characters are literal props and not real people. However, for you, due to the fourth wall breaking aspects, when you take the evil route the characters who are aware of it like sans have to interpret this through the lens of if you were a real person doing these things. And so the narrative interprets you the player as a cold being with no attachments to others. Flowey is depicted as more sympathetic on this front despite his malevolence, whereas chara is depicted as closer to outright unshakable evil. But you as a player it leaves more ambiguous, though your actions on the evil route start to overlap with chara even though they ultimately tell you they grew beyond your control. At the absolute end, if you restart the game after genocide, chara allows you to go back in time to restore the world in exchange for your soul. But he also talks about your nostalgia. A feeling he cannot understand. Showing his lack of attachment to the past.

Unity

Although this one is a bit obvious, one of the points it makes revolves around how exactly to take a higher path, and what exactly it entails. Notably, it is obviously advocating a nonviolent approach towards things, with the good ending being referred to as pacifist to drive home what its core element is. Specifically emphasizing a leaning away from violence in situations that might at first seem to call for it.

However, there is a bit more to it than just that. Which in the context of the game, despite the kind of binary outcome for actions in terms of how it is morally presented as you go on, it begins in a more ambiguous light. Noting that at the beginning, this seeming binary of ethics does not exist, and the actions as they are shown seem to be more morally grey. Meaning that this slant of avoiding violence is something that should also be taken under ambiguity. While the point itself might not seem to have much content, it is the mode of expression, and emotional tone it is done with that drive home how it is meant to be seen. This makes it different in tone from the idea of an obviously pacifistic answer, saying that in real situations it might not look like the most obvious solution.

Despite this, the game does not make the point that you can solve things in that way all the time. Notably, although you can avoid killing them, you do ultimately get into conflicts. And asriel says at the end that avoiding violence won't always be possible in every case in real life. Part of why it is in this case being shown to be the meta aspect about it not being an immediate danger from your perspective. Though it also hints at the reality of someone willing to do so even if it put them in danger, which the character is doing even though you as a player are presented as having it more easy.

While in the immediate sense of the game this might be obviously just understood as literally not killing, the concept of striving for peaceful relations extends a bit beyond this. And into an everyday approach as well. To get the good ending doesn't just require not killing, which is only the basic requirement. It involves taking a step beyond this, and making peace among various people, making bonds along the way. showing that this emphasis on unity over strife is one that is not just a statement about literal harming, but about aggressive versus peaceable forms of relation and understanding in general. Which again, while this theme might seem a little obvious, it is the way it is shown and the tones for which it is shown in that most emphasize cause for reflection and a means of making it more hard hitting.

This of course overlaps with many of the other themes, since the concept of preconcieved notions likewise applies to one's assumption of inability to resolve things in a peaceful way. Something that while it may be true at times is more often not the case than it is, and as the game is making such a point definitely is more often than not. This also speaks to the nature of the distinction between you and the character. You as a player are ultimately deciding whether frisk or chara has control in any given instance. Which is also why on the neutral route they are not identified as distinct figures from you, and each only are in their respective ending. But while sans judges you for your ability to go back but being willing to hurt people anyways, the distinction here is that frisk as a character is not aware of this ability. But puts themself in harm's way to avoid hurting people regardless due to their unshakeable faith. Which emphasizes the optimistic and compelling narrative being shown. Note that the game also shows a darker side of trust

Emotional tones

One of the main aspects of undertale is its wide variety of emotional tones it applies to different scenes. These can range from uplifting, optimistic, playful, lonely, forlorn, depressing, annoyed, guilt-ridden, and many things in between. Even fearful, for the final area in the good ending, which is presented as a horror type area. It manages to fit in a lot for being such a short game, with how quickly it can shift being one of the unique aspects of it. These tones are not merely plot elements, but are thematic as well, being used to convey ideas, such as being part of an overall uplifting narrative for the story as a whole, and for the evil route, using a guilt based motivator as a bait to make you step back and reflect on the overall experience. Many subtle things add to this, such as the quiet and reflective perspective given by the fact that the main character's eyes are always closed. Overall, the focus seems to be on depression, and various negative or reflective emotions, and the path to overcoming them. While there is more than is listed here, this will focus on the most notable examples.

One of the major emotional themes of undertale is tenacity. Referred to in game as determination, it uses the idea in its tagline for much of the game. Although there is not much to describe about this aspect, one of the things it does is show how your feelings of what you can accomplish are related to emotional tones and drives. The plot is set up in a way that many feel makes a compelling strong drive toward giving the player an uplifting feeling, giving them strength to make it through hard times. The repeated messaged of you being filled with determination, despite coming off simple go to show that this self identity, and encouraging tone can affect your real life self-perception. With one of the most compelling, yet strongest being the last fight on pacifist that inverts the statement of “never give up” phrasing it as an already existing quality of you that you never give up. Pushing you to identify with this message and internalize the tone of perseverance.

Much of the game embodies a subtle, but recurrent underlying of a reflective tone. This tone inherently brings up the idea of self reflection on the events and concepts contained therein, and application of them in the larger sense. One way this is shown is with the closed eyes of the character. And the quiet, and surreal, and a little foreboding nature of the environments and music in the waterfall. The game also drives home the point of self reflection, with on each ending you running into sans who calls on you to reflect over the actions you have undertaken, and what the connotations of them are.

Nostalgia is also a major emotional tone. The game both opens and ends with the main character in a home, with the opening presenting them as a child being presented with a loving parent. And of course, the game's graphics as a whole are a call back to earlier times in gaming, which for many can imply a note from the past. The calls for reflection and to look back over your actions overlap with nostalgia, and the idea of looking back over your life in general. Seeing where you started, and how far you came. In the neutral ending, it also gives some very chill inducing lines such as despite everything it's still you, and it seems your journey is finally over. The former of those quotes also implying a sense of comforting certainty over your own identity, holding on to yourself despite everything. The emphasis on you as having undergone a long journey reflecting back on the journey of your life.

One of the more obvious emotional tones is the feeling of bonds and connection between others. Showing the good feelings of deepening connections, and how this can help in difficult times. Since one of the main drives of the story comes from the issues that can stem from people being at odds, bonds are an inversion of this, something that can reveal that certain types of strife are needless.

One of the darker emotional tones is one of depression. This is shown as a major factor of flowey's personality, as well as the empty feeling that comes from it. One of the interesting aspects here is the fact that he describes the world as if it was a game, in a way that makes it come off like he sees people as props. Which while the world is literally a game, is also a meta for the description of how people with depression can often see things, not feeling connected, and seeing their actions as not mattering. Like as he says, living without love. With the depiction of him in a literal cycle of the same time period as being presented as similar to the tedium of an empty day to day life.

Another emphasis given by flowey is the fact that he cannot feel anything. This disconnect and this lack of feeling are two sides of the same coin. In many ways, this is literally what depression is. A numbing effect that is not quite identical to prolonged sadness, but often feels more empty. And he describes himself as literally empty in game, with the concept of lacking a soul being used as metaphor. The inversion can also happen. In-game when you show him mercy he says not that he doesn't understand it, but that he can't understand it. Which can depict the actual perspectives of people so demoralized and emotionally inhibited that they don't even understand certain things. The transformative aspects of depression are also shown here in how flowey and asriel are literally treated as distinct characters. There can be a strong aspect of how it is so overpowering that you literally don't feel like yourself.

Sans too is somewhat aware of this cycle of time resets, and feels apathetic due to it, though taken in a different direction. While he acts overpowered by it, it fueling his apathy, rather than totally give in or become violent, he tries to focus on little things as something to do. He goofs off and doesn't take things seriously since he thinks they don't add up to anything bigger, but he tries to stay positive regardless. Despite this, he clearly has a darker streak. In the fight with Asriel, while saving the lost souls, Sans says “Just give up. I did.” and “why even try”. Notably, unlike the other characters, he seems to say this with his regular voice, which implies that he is aware at the time he is talking unlike the others. Notably, sans breaks out of his apathy on the evil route since he finds something that truly matters. Which is what he thought he was unable to have previously.

Depression in terms of the themes isn't just something seen on the individual level, but is also manifested in the society itself. The society is collectively suffering under depression due to its imprisonment, and aspects of this are shown in different characters, or a reason behind their particular depression. So the theme of overcoming it is reflected in the metaphor of the society itself, and its literal location underground, depicting a sinking feeling. So the themes are reflected in the individual and group level, where the society as a whole isn't just part of the metaphor for individual overcoming of depression, but also for improvement of depressive conditions on a societal level.

Obviously one more tone is guilt. Many of the events are designed to make you feel guilty, most specifically those in the genocide route, which is often known for making certain players feel so bad that they can't even finish it. Some of these come in suddenly, during events people didn't realize would even lead to bad ends, such as fighting toriel, and this leads to some players saying they feel cheated as if it wasn't properly giving them a heads-up then expects them to feel bad about it. But that is the actual point. Feeling bad isn't a bug or a punishment, but an experience of the game, and something to internalize to realize that sometimes these events can simply lead as such. And the game's wide emotional tone has both highs and lows that you can experience both sides of for a full experience.

Forms of depression also intersect with the themes of guilt in many forms in the game. Such as in alphys who feels suicidal at times over what she did, and feels like she can't face people because of it. And asgore who is depressed for the same reason. So this can also highlight emotional tones due to their ties with the past, and the need to look forward and move on from them. The way time is shown in the games is interesting due to the emphasis on looking towards the past and future, as well as the emphasis placed on its cyclical world for those who relive one period in time and its relation to day to day life. Alphys is also a depiction of anxiety, showing tense and scattered reactions due to what she had gone through, and isolating herself to a place and interests in which she feels safe in order to avoid there being too much of this. Note that asgore's house is literally all grey except for the colored flowers to represent his dead family. Something that emphasizes what one focuses on, and how the world literally can become grey to you.

Obviously one final tone it expresses is the amped feeling associated with triumph. Despite everything else about the endings differing, there is a bit of this present in all of them. Which shows the similarities of the different paths. In the end, the accomplishments of all of them intersect with determination. Though it is used for different means.

In many ways, these positive and negative tones of emotions are part of an overall pattern. Undertale's plot in many ways is about depression or apathy, and general negative feelings, and the path to overcoming them. Not just for your own sake, but as a wider goal of improved action all around. The constant referral to determination comes off like an uplifting tone, and path to being uplifted as a whole. Notably, it also warns that it is never entirely beaten. Even after getting the good ending, you can return and take the evil one. With sans even mentioning how he was hoping that if you might find what you are looking for you might give up searching, and live happily. But under the realization that this is not necessarily the case. This is what makes the evil route even harder hitting after playing pacifist. The realization that these things can happen and turn badly even after they seem to be going in a good direction. And sans' dialogue emphasizes it in a way that comes off as if the narrative flow is to play them in that order. And it makes the guilt even harder hitting to do so, even inverting the positive ending, something flowey specifically highlights that the game treats as one continuous path.

Moral motivation

The intersection of the points about goodness and emotions is the concept of moral motivation. Namely the drive to be moral. One of the things shown with the themes of emotional tones is that even if we do know what is better we may not necessarily feel compelled to do it. This is not unique to morality, but because our drives and what we feel compelled to, or even able to do is itself entrenched in emotional narratives. The tone of perseverance here is not just about not giving up on yourself, but is strongest in the good ending to show the continuity of you and others, and how this can help others as well, in turn helping yourself and creating a positive mentality because of it.

Part of this is ironically showing how there are benefits even to you from acting moral. In terms of it leading to a more fulfilling life. But it also does highlight how this might not always be the case. Since it admits that it can involve putting yourself at risk at times, and even that in the real world there are times where pacifism won't actually work as a solution. But that part of the dedication to a higher path can mean accepting the various things that come with it, be they either smaller inconveniences or even some larger risks, and then hoping to achieve the fulfillment that comes from it as well.

As a unique topic there is not much to higlight about this however, since the emphasis captured by it are already covered by the themes of both good and evil, as well as the emotional tones in general. But it is worth noting that the game is not treating these as entirely different themes, but as a continuous aspect of motivation in general. Because your emotional tones effect your motivation for everything, including altruistic actions. One of the most important and direct times this was highlighted being how even after you kill him on the evil route, papyrus' last words to you being that he still believes in you, and thinks everyone could do better if they try.

Oblivion

One of the less overt and more subtle themes in the game, albeit one worth mentioning is the reflection on oblivion. While this does not come up in most of the plot, a few aspects, specifically related to side things tie to this idea. If the fun value is set high enough in the settings, in the waterfall you can meet a grey version of the monster kid who is often called goner kid. If you talk to him he says. “Have you ever thought about a world where everything is exactly the same, except you don't exist? Everything functions perfectly without you. Ha ha, the thought terrifies me.” If you leave the room and come back he will then be gone, as if he never existed.

Although there is not much to say about this, it being more of a solemn reflection than something one can elucidate on much, it goes to show the ephemeral and particular nature of existence. That things come and go, and could have never existed in the first place. In-game, this may also be referring to Gaster, who is a character implied to exist in the backstory, but is not in the game itself as if he was dummied out, except done so deliberately. The game functions fine without him, being a reflection on what it means to exist as a necessary thing. Nothing much is made of this, and it is divorced from the main narrative as a whole.

Deltarune

Lack of choice

Although deltarule has only begun coming out, one of its major highlights is the fact that it contrasts undertale's themes of choice with a theme of lack of choice. where undertale gave you options for what to do and held you accountable for the consequences, deltarune highlights early on that it is an inversion of that theme, focusing instead on a lack of choice. the first thing that happens in the game is it telling you that no one can fundamentally choose who they are, with aspects of themselves deriving from outside their choice.

Deltarune deviates from undertale by highlighting early on that unlike undertale where the narrated events are only for the sake of the player, in the world of deltarune the events are all prophesied. Which shows an element of fatalism in that these events ultimately come to pass as stated in the prophecy, raising the question of what degree of freedom was had along the way. This is something that many things that have prophecies don't overtly address, that even if the ending is positive that this level of control over one's fate and the reality that it will self regulate the pre set outcome can still be stifling. (Undertale also mentions a prophecy, but this is far more offhandedly).

This idea is expressed in the game by highlighting that the dark world is literally arranged like a game. With characters who resemble chess pieces, checker pieces, cards and various other toys being the people who make it up. These symbols represent a lack of control in the ultimate sense, since from the perspective of a chess piece its life is determined by things outside of the world it lives in. In a sense, the pieces don't have control over their own lives in an ultimate sense even if they seem to internally. To what degree this is the case is left ambiguous. Since the bonus boss is a character who is defined from being free from this fatalistic paradigm.

This obviously is likewise meant to have real world applications. Ones which highlight the stifling nature of how certain things are outside of one's hands and which you are subject to the whims of fate that carries you along for them. It is notable that while deltarune and undertale differ in their approaches by having two separate worlds, the themes, though seemingly contradictory are compatible in the real world sense since it is highlighting different types of issue, and the balance of control versus lack of control one has in various situations. Though as the game is not fully out, where delta rune takes this line of thought is yet to be seen.

Limits to idealism

One concern that is often aimed at undertale is the fact that while the emphasis on pacifism makes sense in the context of the plot that one could read it as overly idealistic about when that could be applied. However, the game itself did have a few examples that implied it can't always be used. Asgore, as well as flowey can only be beaten by being fought (Though they don't have to be killed directly). And in the end asriel mentions how pacifism may not always work. Though these scenes are placed a little offhandedly.

Delta rune likewise highlights concerns to an overly idealistic approach. Whereas susie is presented as too aggressive, ralsei is presented as too naive and forgiving, healing an enemy which almost results in your deaths. And he addresses the fact that his idealistic approach was dangerous and he needs to be more grounded. Note that none of these examples from either game show the heroes directly killing anyone. But these concerns are still brought up. Where the game takes it from there being yet to be seen.

Emptiness

Although this too has yet to be fully developed due to only the first chapter being out, delta rule also highlights an element of emptiness that is more overt than that seen in undertale. Something noticeable about the character you play as is that right from the beginning you can see that their side of the room is empty, whereas their brother's is not. And as you go on you see that nobody seems to expect them to speak, nor are they implied to have any interests or friends outside of the plot. As if you are playing as something like an empty shell that only exists to carry the will of the player. While this too is a meta thing related to the nature of silent protagonists in games, what thematic applications it has that extends beyond that have not yet been seen. Since the person you play as also has ties to chara, this could say something about the nature of such an approach also.