AI: The Somnium Files sees the return of Kotaro Uchikoshi, director of two of the excellent Zero Escape visual novels, as he takes us on a madcap sci-fi adventure through the inner workings of a super-secret branch of ABIS Metropolitan Police Department on the chase of a potential serial killer using PSYNC technology. This futuristic means of investigation allows detectives to delve into the minds of potential suspects and persons of interest, piecing together puzzles and unlocking distorted memories from within their deepest dreamscapes in order to get to the bottom of crimes – in this particular case who, or what, has been murdering people and removing their left eyeballs in near-future Tokyo.

Indeed, this is a mystery all about eyes and AIs. Central protagonist Detective Kaname Date is himself missing his left eye, an injury sustained in a bizarre incident occurring six years previous to the events of the game, which has now been replaced by an AI unit, AiBa, who can feed him information, grant him X-Ray and Night Vision as well as enable him to zoom in on faraway objects, people and conversations as he investigates crime scenes.

Kicking off with a grisly murder at a fairground, with a victim well known to detective Date, AI: The Somnium Files starts at an almost pedestrian pace and, for the first few hours at least, everything feels a little too tightly knit. The initial characters we come across all seem in some way personally connected to one another and the circle is almost ludicrously small before finally exploding outwards to encompass a wide range of local officials, shady types and much more outlandish fare which we won’t dare to mention here for fear of spoiling any of the fun. Needless to say, this is one absolutely wild ride once it gets going and very much in keeping with Uchikoshi’s brand of surrealism, here fully unleashed within the dreamscapes of a strong cast of characters.

Where the Zero Escape games were first and foremost visual novels, with a handful of escape room segments dedicated to letting you have your chance to influence the narrative flow, AI: The Somnium Files lets players get involved to a much greater extent by allowing them to control more about the order of events and conversations during their time as detective Date.

At any given crime scene or during the interviewing of suspects, you’ll manipulate Date’s point of view, choose background items to investigate in more detail or the order in which he engages with people. It’s not total freedom, you’re unable to actually traverse environments, and for the most part, all dialogue options with every person present must be exhausted before you move on, but it does make the gameplay feel that little bit more involving during the often-long periods of exposition. You also, eventually, get to choose the next area to investigate, a map popping up with a list of venues to travel to. Again, it’s not total freedom and you’ll have to investigate all areas on the map in the end, but giving you some level of choice makes things that little bit more engaging.

Where the game allows a much more exciting level of player control is in the PSYNC sections of the game. Here control switches to Date’s AI eyeball, AiBa, who transforms to a somewhat expectedly voluptuous female human form to traverse dreamscapes, or Somniums. During these Somnium sequences you are handed complete control of AiBa and are free to walk around environments. However, there are catches to this freedom, and it’s here that the real fun of AI: The Somnium Files kicks in.

During a Somnium sequence, where ABIS’ PSYNC technology inserts you into the mind of another character, you are given a time limit of six minutes to solve a certain number of puzzles, or “memory locks” in order to uncover details connected to the mystery at hand. Moving AiBa around the environment will cause time – shown in the top right-hand corner of the screen – to count down quickly, whereas standing still slows it to a crawl, meaning you need to consider your options somewhat before striking out in any direction.

As you move around and approach objects you’ll be given choices as to how you want to interact with them. Depending on the option you choose you’ll use up a certain amount of your precious time, indicated below your choice, but you’ll also have the chance to gain a “TIMIE”. TIMIES can be used to reduce how long it takes to perform an action. So, for example, if smashing a certain wall or lifting a cage is really going to eat into what’s left of your six minutes, you can use one of your stock of TIMIES (you can hold up to three at any time) to help shorten that interaction. TIMIES also come in negative flavours which add to the time it takes to perform an action, so you need to carefully consider how you wish to proceed in order to advance successfully. Running out of time in a Somnium before you’ve dealt with all memory locks will see you fail and need to restart, either from a choice of the memory locks you’ve already solved or from the beginning of the scenario.

It’s within Somnium sequences that you really directly get a chance to affect the flow of the game’s narrative. There are hidden paths and optional memory locks to uncover which take the central mystery down completely different routes and, once you finish one run of the game (our first took us around eight hours and ended in abject failure on every level) you’ll return to a flowchart of events to pick up from any PSYNC section you’ve already played, working on different solutions to its puzzles in order to leave in a completely different direction. You can check on where you're at on the game's narrative flowchart at any time by bringing it up within the in-game menu, and can even jump around timelines at your leisure and replay any of the Somnium sequences as many times as takes your fancy.

Fans of the Zero Escape games will feel right at home here, and it really is only once you’ve worked your way to the end of your first narrative thread that AI: The Somnium Files begins to take flight and reveal just how many layers it's composed of. Again, we won’t go into details for fear of spoiling anything, but going back over events and finding new ways to proceed adds layer upon layer to the story, giving even more depth to its well-written cast of characters; the odds stacking and drama escalating as you strike out in various directions, with things getting more outlandish and fraught with danger as you do.

There are encyclopedias full of detailed character profiles and explanations of the technical terminologies and wild theories explored within the game to unlock and peruse as you make your way through the various strands of investigation, and you'll also gain access to lots of character art and design sketches by fulfilling specific tasks during certain Somnium sections.

Those Somnium sections themselves are a delightful mixture of abstract and surreal creations and the highlight of the game overall; some ridiculously childish fun, others full of nightmarish imagery, although this does sometimes lead to puzzles which have no real sensible answers, in turn leaving you to guess at what to do, resulting in some inevitable failure at times. However, it’s in this cycle of failure and retreading ground that you’ll reveal most of the hidden motivations of the cast of characters and branch off into the different areas of the story, eventually getting a handle on where you need to go in order to finally solve the mysteries at the heart of the tale. It’s an impressively engineered thing and it took us some 20 hours with the game before we’d wrapped up most of the juicier threads of the story.

In terms of characterization, it’s really only in Kaname Date that things, at points, fall down. Earlier in the game, before relationships between characters develop properly, he comes across as more of a prize douche than a hardboiled neo-noir detective. He seems much more interested in observing and commenting on the breast sizes and attractiveness of the females surrounding him than doing any serious questioning in early scenarios, but this does settle down and he eventually regains his composure and focus as the drama envelops him.

Other characters, such as AiBa, your AI partner, and Iris, the YouTube-style Idol who becomes central to proceedings, are fabulously well-written characters full of pithy comebacks, philosophical musings, conspiracy theories and smart-assed responses, who on more than one occasion save Date from himself, with AiBa constantly keeping our easily-distracted detective on the straight and narrow.

Slight niggles do rear their head in the form of conversations with characters that are sometimes a little too drawn out, and it's a shame the game doesn't give you the freedom to ignore some lines of questioning as knowing you need to ask every character onscreen every question that's available can, at times, become a little tedious. However, for the most part, strong writing across the board and some extremely enjoyable and wild tangents of conversation – sprinkled with plenty of zany humour – avoid this becoming a massive issue. There were also a few points where our progress was impeded by the need to be pixel-perfect in finding some finicky little detail in the background of a scene; again, no big deal, but an issue to be aware of nonetheless.

With regards to the technical aspects of this Switch port, in both docked and handheld modes, things run flawlessly here and overall AI: The Somnium Files is a typically gorgeous Spike Chunsoft creation, with Akira Okada and Yusuke Kozaki’s trademark stylish character and environment designs helping to bring to vivid life the wild philosophical sci-fi visions of its director.