If I think back to some of the games that I started playing years ago, and think to the ones that stuck...
- Pacman. Actually, I wasn't a huge fan, but I actually played it again within the last month, and I saw my roommate playing it recently as well. Simple, even dumb game, but helluva staying power!
- Super Mario Bros. While it's true that the game came with the original NES and so its popularity was partly due to EVERYONE having one, it was one game that most kids I knew would learn to finish, and THEN would go back and try to finish it over and over again, getting higher scores, beating quickest-win records, or even trying to see how long they could play for without dying. The popularity of later Mario games came mostly from the fact that people couldn't get enough of the first SMB game.
- Doom/Quake. I'd class Doom and the whole Quake series together, and I'd say that while the games improved, the idea of the game was simple and effective enough from the beginning that not only did people keep playing them over and over again, but I think I could sit down and enjoy playing Doom again.
- Tetris. You can tire of playing it but you'll always be able to come back and play again. Another of those simple but mesmerizing game concepts that are interesting despite the lack of smoke and mirrors (ie. snazzy graphics that distract from the game's lameness).
- Warcraft. I've known people who had to treat Warcraft like a drug (small doses, withdrawal) because it was so addictive.
- Civ. Sames as for Warcraft.
- Grand Theft Auto in various variants. Again, it's an innately enjoyable concept. People enjoy smashing cars up and wreaking havoc vicariously.
- Nethack. It amazes me sometimes that I occasionally still play this game. I've played some of the graphical versions but it shows the "stickiness" of the game that it can have no eye candy whatsoever and still be addictive.
