Been some good nominations already, so I'll just add ones I haven't seen:
Secret of Mana (SNES version, of course)
Tetris Attack/Panel De Pon/Pokemon Puzzle League.
Tetris Effect. And while we're talking about them guys: Rez!
Spelunky, and Rogue Legacy.
Lest but not least: Roller Coaster Tycoon 2 (via OpenRCT2 these days) - this one I might just fire up in a couple of minutes. Again!