The older games I usually return to are MoO ('93), MoM ('94), and and SC2 ('92). But newer games take the lion's share of my gaming time.

As most people who've been here a while already know, I'm a huge addict of Lords of the Realm 2. Apart from that it's probably Black and White or Kohan 2.

Uhm, let's see....

Dragon Buster from Namco under MAME (1984), Lode Runner from Broderbund under DOSBox (1983). These are the oldest ones I still play "fairly" often, as far as I can tell...

Final Fantasy 7! & 8

X-com mostly.

If I could be arsed to buy a new joystick I would have never stopped playing Tie Fighter, too.

thanks i really want to get far with that game i want to play 4 to 7 wich i got all.

Probably Dungeon Keeper, it gets loaded up for a playthrough every 18 months or so.

Hmm, I have copies of a lot of old, fun stuff (Zork, Bard's Tale, etc.) but I never play them:(

on the playstation 3 you can buy wizardry wich is very old game i played the demo but its too diffecult.

as the title nor the op do not specify PC game, I'm going to "cheat" and say I still play my Atari 2600 games. :D Asteroids all the way!

If that is too much of a stretch, then how about Commodore64 games? Cos that is, technically, a "PC" after all!? WizBall FTW!

Still no?

Tough crowd. Ok then I'll have to say Solitaire then. Completely boring option, but honestly its pretty rare for me to go a week with out having Solitaire open at some point.

I think Daggerfall has the best dungeon crawling of all the Elder Scrolls games. Except maybe when your supposed to kill a specific enemy, and he just isn't there. I spent hours and hours searching dungeons over and over in that game. When I finally find that pesky Orc Warlord or whatever im supposed to kill, he is hanging around in a room that I went through like 10 times already!

Civilization 1, Mac version. At least one or two times a year.
The best one in the series In many ways.

Bunch of C-64 games I'd still play if I had one.
And now that I think about it. I'll have to find an emulator and give Phantasie III a go.

I know the version of Tetris on my phone is a bit different from the original, but it's Tetris and that's that. I think i play it at least once a week, usually while waiting for a lecture or whilst sitting on the throne.

Dungeon Master (1987) + sequels

UESPwiki (google that) has quit a lot of hints and information about the game (actually all TES games). That might help you creating a better character.

Quite a lot of them, but the most often would be the first Diablo. Very relaxing game.