I never get tired of playing Kaamari Damacy. I do not know why. It's just utterly bonkers fun.
Retrogaming
Playing games on or emulating past-generation computers and consoles.
Tetris. That game has aged extremely well. I played it on the original Gameboy. I last played it on a VR headset.
Capcom vs. SNK 2. It's good to the last drop, no matter when and where you play it. Bloody Roar: Primal Fury/Extreme also holds up far better than Sega's Fighting Vipers series.
Neo Turf Masters. Picked it up recently for the first time and it's the first time everything in a golf game has just intuitively clicked with me in terms of "oh, that's what each club does". Throw in fast pacing and simple controls and I got really hooked in a way I never do with sports games personally.
I almost always have a new run of Knights of the Old Republic I or II going. It's almost 20 years old and the replayability still amazes me.
Mike Tyson's Punch Out!
Symphony of the Night. I played it for the first time a few years ago, and it holds up really well next to modern metroidvanias, better than Super Metroid IMO.