1. Knytt UndergroundIs this the best looking game on my list? No. The world design is pretty gorgeous, a mixture of black foreground and colorful backgrounds, but the character designs are... not as great, very basic and not particularly appealing. That doesn't matter. Is this the hardest game on my list? Not at all, there's no real difficulty curve to this game due to its nonlinear progression, and even at it's hardest it's not too tough. That doesn't matter. Is this the largest or most varied game on my list? Nope, runs about 20 hours at max and primarily sticks to its two main styles of gameplay without really having any extra side missions. That doesn't matter.
Simply put, playing this game is one of the best gaming experiences I've ever had. The first time I played it, specifically, but due to the sheer size of the game map it's actually quite replayable, since every playthrough is going to be quite different just by necessity. There's just something about getting lost in this strange but slightly familiar world, exploring the many different areas of the tunnels. Some of them beautiful and soothing, some of them unsettling or outright terrifying. It's really all about getting lost in the atmosphere of the game above all else for me, because it's probably the best and most compelling atmosphere of any game I've ever played. And the soundtrack definitely helps with that; a lot of chill ambient stuff but it's very moody, almost always matching the environment each track plays in perfectly.
What is the gameplay like, you ask? Basically, it's an exploration platformer - specifically NOT a metroidvania, as once you hit the main game after the two short tutorial chapters, you're free to go almost anywhere you want to immediately.You play as Mi, who can climb any vertical wall, though not across ceilings, and the only other move she has is the ability to jump. And due to shenanigans, Mi has ended up fused with Bob the Ball, whose gameplay mostly consists of bouncing around, using momentum to get to places Mi is unable to get to herself. It's an interesting mix of more precise but limited platforming and less controllable but more free platforming, and there's a lot of interesting scenarios set up across the game's world.
There's also some platforming puzzles centered around the colored orbs of light you can pick up which generally give Mi a bit more mobility (or an actual attack, which she lacks normally) and there are again quite a number of interesting puzzles based around these. As with Environmental Station Alpha, one thing that makes exploration in this game really enjoyable is the fully dense map - and here, the map is quite a bit larger, a solid 48 by 30 rectangle of rooms, nearly 1500 rooms in all, even discounting the secret stuff lying outside of the main map. And with a few exceptions, a few small areas locked off by quests, you can get anywhere you want, so if you see a hole in the map and don't know how to access it, you're usually just missing a hidden passage into the room tucked away somewhere not quite obvious.
The game also features quite a number of quests, which tend to be just going off and collecting an item or two in the overworld and returning to the NPC, but there's usually a small bit of story tied to each quest, and some of them can get pretty interesting. It's small peeks into the lives of the other denizens of the underground, and often they reveal the lore of the world in bits in pieces alongside the small tasks accomplished. The game brings up a lot of philosophy and moral dilemmas but it never really forces the answers down your throat, just leaves them there for you to think about. Oh and the moral choice system of the game, yeah. Mi is mute and has two fairies who have to do all the talking for her, and while they start out as "the nice one" and "the mean one" there's far more depth to their characters than that. There are even some quests you can't start until the fairies have developed more as characters, and it's really interesting to see the two very basic personalities fleshed out into interesting characters.
The overarching plot itself is pretty basic - Mi has to ring 6 bells or the world is going to end... maybe. And the game is set after some apocalyptic event that ended all life above ground, leading all the surviving creatures to take up residence underground. One of the common elements throughout the game is human technology being vastly misinterpreted - but not really in a comical way, more of a "what would other beings think of human technology and language if they had absolutely no context given and had to make assumptions themselves". And there's even a god metaphor pushed onto humanity itself, but not in a preachy way. The writing as a whole is generally just pretty clever, decently funny and usually pretty smart, while having its main characters develop during the long journey.
Honestly I could probably ramble on for hours about how incredibly good this game is, and how everyone should go play it and experience it for themselves and all but. You really should, it's #1 here for quite a good reason. No frustration to be had, no unpleasant or stupid themes, just great atmosphere and enjoyable gameplay and a lot of surprisingly unpretentious philosophy that really does make you think. To think that I got this game from a bundle without really thinking much of it at the time, and when I did get around to playing it I loved it enough to consider it one of my favorite games of all time. And heck, it's my favorite now, apparently, unless something comes along that I enjoy even more. Excellent game. Probably not for everyone, but for me it's just... the best.