For me it was Terraria, Satisfactory, Tetris Effect Master Mode, Minecraft with Mekanism mod & CSGO / CS2 (almost 2000 hours in CS alone).
Edit: There are so many answers that I might only reply if I have something interesting to say. I will read all of your answers though. 🙂
Edit 2: It has become too much for me and I have to disable notifications. Thank you for the massive response and please continue to discuss with everyone here. ❤️ 🫡
Operation Harsh Doorstop multiplayer - I can’t get enough of Project Reality style semirealistic battlefield games.
Motortown: Behind The Wheel - the driving just feels so damn good…
Cataclysm Dark Days Ahead - specifically Sky Islands mod to give the game a more “run based” focused feel. This game has passed an event horizon of environmental richness no other adventure game comes close to, the landscape truly feels alive and it is very addictive in a good way.
Call Of Duty Mobile & Other Battle Royale Mobile Games - such as (now defunct) Apex Legends Mobile or Farlight 84, never spent money on it in addictive way I just find higher level competitive battle royale gameplay fascinating.