I play Tetris online a lot. I've always been a huge Tetris fan, and I still have my original 1988 Gameboy Tetris cartridge!
I beat Super Mario Bros 3 when I was a kid, but I don't play any other computer or video games. Starting in the mid 90s game graphics, especially first-person, started giving me severe motion sickness. The first time it happened was watching my mom play Journeyman. Just a few seconds of a modern game is enough to make me dizzy and nauseated -- which is ironic, as I've never gotten motion sickness from actual motion. I still break out my old gameboy on occasion, and I beat Super Mario 3 for a second time about 6 years ago when I was really depressed for a month.