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. ๐
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. โค๏ธ ๐ซก
I think most here are too generous with the term addiction.
I had to uninstall Hearthstone years ago, because I compulsively played it multiple hours every single day, despite not really having fun playing it anymore. It was either grinding to get cards or tilting on ladder. That's what I would call an addiction.
Edit: After Hearthstone I played a lot of Slay the Spire and after that Marvel Snap. Never more then I enjoyed it, so I wouldn't count those.