Honestly, just playing a random game of the NES, SNES, Sega Genesis, or even more recent titles (Ace Attorney comes to mind) usually fills my gaming needs. I've recently been playing Deltarune, which, as a small little gremlin that installed it back in the day with a patch for it to be in spanish, brings a smile to my face.

As for specific games... Hm. I'd say that ULTRAKILL,Balatro and the already mentioned Deltarune are the most regular on my screen and my personal recommendations. Retro favorite has got to be "Punch Out!" for the NES, though!