1 - Super Mario Odyssey
The long-awaited successor to Super Mario 64. I'm not gonna say sequel because that's what Sunshine is, and that game already gets enough vitriol. Mario is back to feeling like a joy to play and Cappy brings an interesting gimmick that justifies the vibrant worlds of the game (since you can literally become part of it). I also think the bosses are great, including the Broodals that everybody seems to hate. The game is more or less a big celebration of the franchise, with "Jump Up, Super Star" being legendary.
2 - Donkey Kong Country: Tropical Freeze
A.K.A Fucking Donkey Kong. This one deserved so much better treatment when it was first revealed. Excellent level design, soundtrack, bosses and animations, with Dixie and Cranky keeping the gameplay fresh with new movement options (Dixie in particular breaks the game). I'm glad that the Switch managed to gets its own Funky-tastic port, but that alone probably can't undo the damage associated with the Wii U entry.
3 - Super Mario 64
The one that revolutionized Platformers. Hasn't aged that well and I still criticize it every so often because of the repetitive nature of the courses, but I cannot deny how important this game was to the industry, and that alone probably warrants a high spot. Mario still feels really good to play despite the game being 23 years old and at the forefront of the 3D janky era.
4 - Mega Man X
It's Mega Man! Except not. It's much better! I respect the OG Mega Man for everything it brought to the table, but I think MMX is what happens when you bring the MM formula to its full potential. In fact, the word "potential" is highly relevant to this game since it's the story of a robot in a somewhat dystopic future working his way from the bottom of the ladder in order to keep up with or even surpass the coolest guy he knows. The dynamic between X (whose name represents a variable) and Zero (whose name represents a fixed value) is excellent and adds to an already interesting setting where machines can go rogue at any minute.
5 - Super Mario World 2: Yoshi's Island
Yoshi was the best part of Super Mario World, so making him the star of the "sequel" was definitely a genius move as it was turning Mario into a baby so his origin story could be told. I'm incredibly glad that Miyamoto stuck to his guns and didn't succumb to the pressure of Donkey Kong Country, giving Yoshi's Island a handicrafted look that complemented the narrative of the Yoshis acting like caregivers themselves. In my opinion, Yoshi's Island's credits sequence is perhaps the most satisfying and tearjerking moment of any Mario game, or even Platform Game, that comes to mind.
6 - Ratchet & Clank: Going Commando
More or less my gold standard for Ratchet & Clank games. The first game is pretty good by itself, but needed some extra polish that was thankfully done through this sequel. Weapons can now be upgraded, Clank automatically changes into the appropriate traversal tool and Ratchet feels more tolerable as protagonist (while not as boringly nice like he is currently). I also have my grievances with the third game that are similar to the ones presented by TheGamingBrit's
video about it. I feel like having the R&C duo travel to a different galaxy while on a secret commando mission helped in making things just as fresh and isolated as the first game, since Up Your Arsenal revisits several locations from the original and focuses too much on Qwark's team of useless idiots (I was not keen on the war aspect of UYA since I prefer when R&C do things at their own pace without direct help). I also really miss the jabs at consumerism that were present in all PS2 games as the more recent entries have all but abandoned that angle in order to focus on more generic space adventures.
7 - Psychonauts
I'm really, really, REALLY glad I got to play this game back when I had the chance. It has those 90's Adventure Game vibes all over it, but without the slow point-and-click gameplay that's not for everyone. You can have a lot of fun yourself by just learning to levitate and bouncing your way around. I also enjoy the little stories behind all the campers and how their dysfunctional home lives led them there. It's already pretty great when it's only you dealing with camp life and collecting all those buried arrowheads and psychic cards, but Psychonauts becomes a true masterpiece from the moment you face the lungfish and reach the mental asylum.
8 - Crash Bandicoot 2: Cortex Strikes Back
A complete improvement of the first Crash Bandicoot game. Crash actually feels great to move around and the levels now have actual variety instead of being stereotypical jungle adventure courses with a few industries later. They also made Gems less unbearable to collect and the "death paths" are a cool way to add challenge to the game. The third game is perhaps just as good in certain areas, but feels somewhat gimmicky due to all the vehicular stages. The second game has those as well, but they never overstay their welcome, especially because they are mostly additions to levels instead of being the whole level itself.
9 - Kirby Super Star (Ultra)
Still the king of Kirby games. I particularly love how it consists of a compilation of mostly standalone stories where Kirby has to deal with increasingly dangerous threats ranging from the local glutton despot to an universal wish-granting satellite clock of the apocalypse, with each story having their own unique little gameplay quirk like the collectibles from Great Cave Offensive and the instant transformations from Milky Way Wishes. The combat is definitely the aspect that was most improved from "Kirby's Adventure" and the biggest reason why it felt so great to play as every transformation now had their own varied moveset of acrobatics, grapples, charged attacks and so on. The Ultra remake is even better with the new modes it adds, but I don't really like to count it as a separate thing.
10 - Kirby 64: The Crystal Shards
This is one I have plenty of nostalgia for. It gets some mudslinging on for not being "Kirby Super Star"-like, but it has its own interesting mechanics that help it stand out among the countless Kirby games out there, like the fun ability combinations and friends that helped you out with puzzles or obstacle courses. It also did some cool tricks with 3D perspective that current 2.5D Kirby games rarely attempt, making this game feel a lot livelier than later entries. The secret final boss is also highly memorable, even if it's quite easy.
Upgrades: Mega Man X. This game is X-tremely good (I do not regret the pun) at portraying X's growth, no thanks to the presence of powerhouses like Vile and Zero making you feel like a weakling at the start. From then on, you learn how to dash, break walls and charging weapons by finding Dr. Light's ghost/hologram capsules. All of the Maverick bosses' weapons also feel useful in a broad way instead of something that's only necessary for specific situations. Also, the Hadoken easter egg has to be one of the most insane secrets to a game I've ever seen, like the sort of ridiculous videogame urban legend you used to read in old magazines, except it's real in this case.
Story: Celeste. It's not in the list since I don't value story in games that much, but I would be lying if I said the game's themes didn't resonate with me. "Sometimes, we are our own worst enemy" is a universal message that will never get old.
Soundtrack: Tropical Freeze. David Wise really propped this game up with his talent. The variety is superb. There's calypso, polka, indigenous, heavy metal, etc. and it all sounds good.
Mechanics: Super Mario Odyssey. No thanks to how good Mario feels to play. They took the moveset from Super Mario 64 and expanded it to a significant degree. Cappy was also a welcome addition, with the possessing adding some great variety for traversal and puzzle-solving.
Level Design: Tropical Freeze.
Game Maker's Toolkits did a great job exposing this one to the world. Retro essentially took the Mario formula and added their own ambitious twist to it.
Art: Psychonauts. This is "Modern Art: The Game". Gotta love the twisting neighborhood of "Milkman Conspiracy" and the dark neon brightness of "Black Velvetopia". Then you have Sasha's minimalist cube mind, Milla's trippy disco party and the level that's a literal theater play in the mind of a bipolar person. It's really amazing.
Boss: Banjo-Tooie. Not on the list either, but the bosses were one of the best parts of that admittedly bloated game. Mr. Patch and Mingy Jongo were a riot, while Weldar still terrifies my dreams.