OMORI is incredible. The gameplay is okay (typical JRPG stuff), the music is okay (I've heard better in other games), but the storytelling is some of the best in all of video games, up there with Silent Hill 2 and 3.
The Binding of Isaac is an incredibly addicting game. It's basically rougelike 2D Zelda dungeons, and upgrades stack on top of each other. It's the game that I have the most hours in on Steam (specifically the much better-programmed remake, Rebirth). The DLC is great as well, adding a ton of content. Its replayability is damn near unmatched.
Super Meat Boy is just a really fun, fast paced 2D platformer, that is challenging, but fair. The controls are some of the best of any 2D platformer out there, beating out both Super Mario World and Yoshi's Island IMO.