AI: The Somnium Files – Nirvana Initiative review: the best detective puzzle game this year

AI: The Somnium Files – Nirvana Initiative is a riveting, time-hopping murder mystery from the minute it begins until its closing moments. Written by Kotaro Uchikoshi, who also wrote the excellent Zero Escape trilogy, Nirvana Initiative is just as effective as a singular story as it is a compelling sequel to 2019’s AI: The Somnium Files. It’s a well-paced visual novel wrapped in detective conceits and packed with surprises at every corner.

The game follows two protagonists: returning character Mizuki Okiura and new guy Ryuki Kuruto. They’re both Special Agents of ABIS, the Advanced Brain Investigation Squad. The members in this unit within the Tokyo Metropolitan Police Department “psync” with suspects using a large machine in order to dive into their subconscious and uncover their secrets.

The game jumps between two different time periods, six years apart. When the right half of a corpse is discovered in the earlier timeline, Ryuki and Mizuki are both sent down a bizarre rabbit hole — their search for the other half comes up fruitless until six years later, back in the present day. Mizuki and Ryuki each have AI-Balls equipped in their left eye sockets, named Aiba and Tama, respectively. They are autonomous AI that assist investigations with x-ray vision or complex calculations.

Nirvana Initiative is primarily a visual novel in which Ryuki or Mizuki travel to different locations throughout Tokyo to investigate crime scenes. Once at these locations, the player can switch between x-ray and thermal vision to interact with pieces of evidence. After collecting all of the evidence, Ryuki and Mizuki reenact the crime, while their AI-Ball partners comedically pretend to record them like a TV show. During these segments, players will need to correctly select and place the evidence within a timeline.

Image: Spike Chunsoft

At certain points, Aiba and Tama plunge into “Somnium” dungeons, which are manifestations of a character’s psyche. You learn more about the characters and their backstories by solving Somnium puzzles about their past lives. For example, an egotistical maniac who’s obsessed with genetics (bordering on eugenics) has an entire dungeon dedicated to creating perfect human specimens.

All of the Somniums are wildly creative, even when the story necessitates going into the same character’s Somnium more than once. One particular dungeon is called “Kusemon Go” that pays homage to the ever popular Pokémon Go. Its aesthetic and mechanics match the monster collecting game, too — you have to “catch” some of the main cast and use them to “battle” gym leader-like NPCs. Even the dungeon’s music sounds as if it were composed using the chiptune route songs you’d hear in mainline Pokémon games.

Nirvana Initiative’s script is laden with references to real-world conspiracy theories (the primary one being that the world is merely a simulation). What makes them fascinating is that they use real scientific theories to try and explain them, like the holographic principle and the double-slit experiment. In this way, the story is equal parts grounded and farfetched — a tantalizing mixture of logic and mystery. How the characters justify such outlandish, conspiratorial beliefs is incredibly interesting, and makes you wonder if maybe, just maybe, they might be right.

The narrative builds to a stunning climax, which comes in the way of a revelation that recontextualizes everything that’s come before. I was already glued to the screen, obsessed with trying to figure out the motives and identity of the killer behind the half-body murders — but the plot twist made me change the way I interpreted events going forward. In the game’s final act, I was all but sure that another curveball was coming my way. I won’t spoil whether it was.

Image: Spike Chunsoft

It also helps that Nirvana Initiative’s cast of characters is delightful. As the rookie on the task force, Ryuki wants nothing more than to impress his superiors. He stands in stark contrast to the first game’s protagonist, Kaname Date. Date’s pervertedness turned some players off, as it sometimes clashed with the game’s darker moments.

Ryuki is much tamer, but he’s surrounded by a mysterious air. Throughout the game, you get the sense, through his dialogue, that something’s not quite right about him. To compensate for Ryuki’s reticence, Tama, his voluptuous AI-Ball, often makes sex jokes. Whereas AI: The Somnium Files’ frequent use of innuendo could throw off tense scenes, Nirvana Initiative is more clever about when it deploys its comic relief. It knows when to lean on levity, and when to let its gruesome murders propel the action forward. In the first game, Mizuki was incredibly defiant of authority, and I’m glad they dialed up her rebellious personality even more in Nirvana Initiative. Her lines are sarcastic and funny, often balancing out Ryuki’s more by-the-books attitude.

Lastly, the dialogue throughout, whether in its grim moments or lighthearted bits, is supported by fantastic English voice acting by Corina Boettger and Erika Harlacher, who reprise their roles as Mizuki and Aiba. Newcomers Stephen Fu and Anairis Quiñones do a fantastic job as Ryuki and Tama as well.

Image: Spike Chunsoft

In terms of structure, Nirvana Initiative is extremely linear, and thus, constricting. In the first game, and in the Zero Escape series, Uchikoshi and his teams provided enthralling narrative flowcharts. Nirvana Initiative’s flowchart doesn’t have as many opportunities to explore events on your own terms. Instead, you’re almost entirely railroaded into playing Ryuki’s part of the story the entire way through first, and then Mizuki’s. All in all, it’s a more tailored storyline, and it may feel more manageable for players new to Uchikoshi’s scripts — but I found myself missing that overwhelming web of plot paths to wander.

Another smaller gripe is that the loading times can be unusually long, even when playing the PlayStation 4 version via backward compatibility on PlayStation 5. The main menu is a bit unresponsive, too, as it takes a few clicks before I’m able to get to the save game button. But none of these issues were detrimental to my overall experience, and I didn’t encounter crashes or anything game-breaking.

AI: The Somnium Files – Nirvana Initiative boasts a compelling story, along with some great plot twists that caught me completely off guard. Its investigations are intriguing, and its Somnium dungeons are both colorful and foreboding. Nirvana Initiative is an incredibly eccentric game, bursting with vibrant characters, mind-bending puzzles, and an abundance of strange sci-fi detours. And once it builds momentum, it doesn’t let up. It wouldn’t be a stretch to say I love it.

AI: The Somnium Files – Nirvana Initiative was released on June 24 on Windows PC, PlayStation 4, PlayStation 5, Xbox One, Xbox Series X. and Nintendo Switch. The game was reviewed on PS5 using a PS4 pre-release download code provided by Spike Chunsoft. Vox Media has affiliate partnerships. These do not influence editorial content, though Vox Media may earn commissions for products purchased via affiliate links. You can find additional information about Polygon’s ethics policy here.