I have a personal soft spot for Doki Doki Literature Club because it got me into programming when i was young, but that’s far more sentimental and to be honest i wouldn’t play it again as an adult really. If i had to pick something functionally though I’d say Project Zomboid. there’s a fuck ton of fun to be made in that, especially with Multiplayer. Even in singleplayer i like to turn on a NPC mod and assemble my own makeshift Walking Dead cast