Felt inappropriate rating this anything but a 9.

This one left me very happy at the end of it. The game's hardest swing at its surface is probably its endgame reveal that the game's six branching routes are all parallel timelines between which our protagonist, Junpei, subconsciously transfers his own consciousness to ensure everyone's survival. As fun & clever as this twist on a time-tested VN structure is, it belies what I think is the truer core of the game's impact: its cast dynamics.

All the timey-wimey-wibbly-wobbly stuff would run the risk of feeling emotionally empty without juicier meat like the simple yet effective blossoming romance between Junpei & Akane; the intimacy of our last-minute main antagonist - group dad turned murderous schemer Ace - as a final obstacle; the constant threat of tragedy looming over siblings Clover & Snake; Lotus' enormous milkers; and the all-around charm & heart packed into every line of dialogue, bolstered by a camaraderie fostered by the palpable tension of the Nonary Game setup. This isn’t to say there’s no merit to be found in the overarching system, or the almost self-indulgent amount of little twists on Zero's part, but the two halves of this semi-romantic sci-fi drama definitely elevate each other to greater heights.

The gameplay itself isn’t exactly anything to ride home about, but I think it understands its place in the bigger picture of the game. There are 16 puzzle rooms in the game, all of which are fairly easy & uncomplicated affairs. Regardless, the game does introduce some escalation, particularly behind doors 1 and 6, and the puzzles remain engaging throughout without ever detracting from the pacing of the ongoing plot or time given to develop the characters (with multiple puzzle rooms pausing to hit critical character beats). My only complaint would be some puzzle rooms - namely the kitchen and confinement room - forcing you to complete them in their entirety despite hypothetically being entirely skippable on a second run, given the core premise. That aside, my favourite puzzle room would have to be between the cargo hold and library.

As a bit of a side note, 999 and the wider series have gained a bit of a joking notoriety for their love of pseudoscientific gobbledegook and, while it’s definitely there, I think this entry does a generally solid job of giving its characters’ rants about fake niche factoids a sense of purpose, either by tying them into the ideas of the main plot or injecting their delivery with an endearing dose of enthusiasm (and a hearty counter-dose of confused sarcasm from Junpei for good measure). No tangent egregiously overstays its welcome and, besides maybe the infamous “ice-9" exposition dump dropped cheerily in the middle of a locked freezer, each one is given appropriate enough context for it to only add to the cast's charm.

Overall, a very strong experience. It won’t rock your worldview or anything, but it delivers a powerful 2-in-1 package of intricate sci-fi gobbledegook wrapped around a deceptively simple love story and a lovable cast thrown into classic escape room drama. The Nonary Games release adds a flowchart for QoL and comes packaged with the best version of its sequel, so pick it up on modern platforms if repeating chunks of routes is too much of a hurdle. Otherwise, I wholeheartedly recommend the original DS release of this game.