Based on my currently highest time spend in the game, in no particular order: Terraria, Dark Souls 3, Factorio + expansion, Stardew Valley.
The last one kinda depend on some caveat: Fallout 4(assuming mods also survived), Project Zomboid(if the dev will still working on it), or dying light(assuming some mods also survived). Else Prey 2017.
Edit: honestly i would put Monster Hunter 4U up there, but not sure if i can still take the early game grind, World kinda ruined a bit of 4U but it still a significantly better game.