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. ❤️ 🫡

  • squinky@sh.itjust.works
    6·
    20 hours ago

    Dwarf Fortress. I think I have ten thousand hours in the classic game.

    Oxygen Not Included for the same reasons. I really like games where you both design, and are affected by, complex ecosystems