Town of salem is perfect. I hop on whenever i have nothing to do. You can leave whenever too usually. or Bloons TD 6
FTL - Faster Than Light. It's a relaxing roguelike strategy game that offers numerous hours of playtime with each run being different.
Most of these have already been said (stardew valley, all of the animal crossings, slime rancher) But mario kart is good you can hop on play a race and leave. I reccomend playing wii (wiimfii for online) or mario kart 8. DS is also great
battlefront 2 is so fucking fun. I recently installed a mod that makes Darth maul Bernie sanders Spoiler: I am once again asking for my revenge