For decades video games have offered fantastic escapes into detailed and memorable sci-fi worlds. But which stand out in our memories? Which sci-fi universes have we enjoyed poring over the most? Below we've compiled 20 of our favorite sci-fi gaming worlds.

Originality - Does the world present at least one fresh idea or concept we haven't seen tackled in fiction dozens of times before?

- Does the world present at least one fresh idea or concept we haven't seen tackled in fiction dozens of times before? Plausibility - The world can be a silly or outlandish place, but does it at least include some foundation in reality we can recognize?

- The world can be a silly or outlandish place, but does it at least include some foundation in reality we can recognize? Consistency - Does the game play by the rules it sets for itself? Is it internally consistent and logical?

Mega Man

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Halo

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Mass Effect

Fallout

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Chrono Trigger Future

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Half-Life

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Deus Ex

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XCOM

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Homeworld

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StarCraft

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All the worlds we selected had to exhibit three qualities:Our 20 selections are focused specifically on how much these worlds sparked our imagination and how much we enjoyed exploring them. There are lots of examples of great sci-fi games that didn't feature especially memorable worlds. And likewise, there are some game worlds included here that sadly didn't have high-quality games doing them justice, but the worlds themselves still displayed a lot of promise.While this is essentially an alternate reality to 21st century earth, it’s the idea that humans created a workforce of robots that is most intriguing. It’s a common plot hook, sure, but the robots had entire collectives designed for one particular task, each of them lead by what is essentially a foreman. The “foremen,” called a Robot Master, have special “tools” and advanced AI to help with their particular task. Then Dr. Wily decides to use them to conquer the world. The most interesting twist is that the underlying idea of Mega Man’s world is all about two doctors - one good, one evil - using robots to battle do battle with each other. Best game of chess ever.Setting aside the epic of Master Chief, it’s both worrisome and humbling to think that all of humanity was created, not by a God or evolution, but by another species, the Precursors. The Precursors created the Flood, Forerunners, even the Halo weapons themselves. It’s as if the universe is a giant sandbox for these creatures, creating and destroying species at will. But they’re not infallible. And though the Precursor’s reach seems nearly endless, we still see it all from humanity’s point of view, focusing on survival and trying to earn a space where we can simply exist.Some of the underlying politics that exist in the Mass Effect series are mirrored in our lives today. Racism, homophobia, political corruption, it all exists, except now it’s on a universal scale. In the game, most of those vices are aimed at humanity as a race. We’re a young culture, naïve to the ways of the universe, and we’re fighting for equality on every front. It’s a shocking reflection of our own society.It’s the memory of a world lost that makes Fallout Post-apocalyptic survival isn’t a new idea, but usually the cause is humanity. While it’s only a glimpse of what lies in the future, the world is hell and humanity is teetering on extinction. There’s no food, the sun has been blotted out, and humanity barely survives in broken down domes. Fear and hunger are in abundance, making it a rare moment where seeing the outcome of failure injects a sense of urgency and realism.Don’t play with strange rocks because aliens will kill you. And while there’s 50 years of history between the time it took Cave Johnson to transform a shower curtain manufacturer into Aperture Science, it’s the events during and after the Black Mesa incident that are the most compelling. First, experiencing the invasion and seeing how a government agency reacts, with policies and implementing training that nobody ever thought they’d use, is dangerously close to how we’d expect it to happen in real life. Second, thanks to Portal, we see the facility run down and decaying, with GLaDOS seemingly in charge. We know that the timeline extends beyond, but the questions linger as to how bad humanity has fallen. It’s the questions that remain unanswered that help make this world one we love.Despite using two Sci-Fi clichés, alternate timeline and Area 51, Deus Ex still manages to put their own spin on the world created. Though it’s similar to our current world in terms of geography and timeline, it implements technology that is far from anything we have now. It’s the similarities to modern-day are perhaps the most disturbing. Corporate conglomerates swimming in profits while the middle-and-lower classes suffer. Government surveillance and near-police states. And, in what might be viewed as a scary piece of foreshadowing, domestic terrorists are striking back against the government. Maybe the world of Deus Ex isn’t that far off, after all.One has to wonder if our own government has created and maintains a division of military aimed at combating an alien invasion. In XCOM’s world, one has existed for more than 60 years and has been pretty successful defending earth. What makes XCOM’s version of the world so incredible, sadly, is the fact that many countries can set aside grievances in the face of real danger and are working together to defeat the threat. Still, aliens bring some pretty handy technology and, with a little reverse engineering, mankind has used it to their own benefit. Of course, scouring any conspiracy website will only tell you that this is how we’ve made many technological advances in the real world. But that’s just crazy. Isn’t it?Instead of a world destroyed, the Kushan are surviving on a world that’s long been barren. It’s all they know, but a discovery leads to thoughts of salvation, of a world where life is easier. Unfortunately, it wasn’t as expected. Knowing that a ship carrying less than a million people is the last hope of your race is stressful, but trying to discover who your people really are only adds to that. Homeworld set the foundation for 3D RTS games and helped create an atmosphere of curiosity among a need for survival.It’s not just another “alien invasion” cliché, but rather a take on war at a universal scale. The quirks and nuances of the different races are succinct, but the political dealings of the Terrans (the humans) make for an interesting setting. With a government that believed in the “Divinity of Mankind,” all humans with mutations or cybernetic enhancements were rounded up and imprisoned. Thousands of these “prisoners” were then frozen and sent off to form their own colonies. The socio-political world that Starcraft created is often overlooked, but is deep and a good example of history repeating itself.