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. ❤️ 🫡
For the entirety of high school I only played Team Fortress 2, League of Legends, and Melee. I have 2000+ hrs in TF2 and probably more in the other two. Then in college I was on the Overwatch team and played in the college league, I have a bit under 5000 hrs in that.
No games I have come close to that kinda play time and none probably will since I have less time to game and I’ve kinda been losing interest in gaming in general.
Community server TF2 was the absolute peak of game-playing in my life. I was laid off from a job in the late ‘00s and just played on a server with a bunch of people I loved for 40+ hours a week. I found a shady key guy I would send money to and he’d give me keys for a buck a pop. Got an unusual towering pillar that eventually bought me an index, a million years later.
Love that game.