Undertale, because Undertale. Also, no spoilers allowed.
Paper Mario, this game really goes to show how a bit of simplicity and personality coupled with great game design can make something very special, also this basically goes for Undertale too, but multiply it tenfold and there you go.
Paper Mario: The Thousand Year Door, this is an excellent example of how to make a great sequel, not quite as charming as the first one though, but just as excellent.
Super Paper Mario, great story with amazing concepts and ideas blended with decent enough gameplay, the main reason to play this is to see how deep you can go into something as originally bland as Mario and still create something incredibly memmorable even if it's very flawed or not very inspiring.
Super Mario 64, how the 3D platformer started, it basically should be used as base of any game of the genre.
Super Mario Sunshine, dem controls are the finest thing I've ever felt, more Mario games should control this way, this is how you take the 3D platformer to the next level by making it felt super smooth and extremely acrobatic.
Super Mario Galaxy, incredible atmosphere, great game design, a very enjoyable trip, a bit flawed with the motion controls segments, but aside from that, everything is just perfect.
Crash Bandicoot 2, this is the textbook defenition of making your game have its own personality, once you hear people say "that track sounds like something out of Crash" you know you've done something right. That aside, apart from a few questionable design choices, the game is perfect, and its difficulty is incredibly balanced. It's also basically the most fun game 100% ever, so that counts for something, I guess.
Kingdom Hearts 2 Final Mix, great music, great controls, great combat, amazing boss battles, entertaining story, all blended with a nice cup of Disney nostalgia, what more could ya want?
Portal 2, play it on one sitting blindly and see what it does to you.
Super Mario Bros 3, just like SM64, this the base that all 2D platformers shoud build around.
Bioshock Infinite, some of the most memmorable moments in gaming, a flawless art direction and a game world that you can practically breathe make this something that you have to experience.
I'm now filled with determination.
