Firstly, I think its interesting that you consider playing games more productive than watching TV. I'm with you and feel the same way, but it is a funny way to look at things. Along that note, if I spend the whole night watching TV, the night feels wasted. But if I stay up until 2am playing the latest game thats caught my attention, its another matter all together.
Most computer games give you a fake sense of accomplishment, making it feel like playing them isn't really unproductive at all. You defend planets from invading demons, save hostages from fanatic terrorists, get shiny new armour for your RPG avatar, command your troops and conquer your enemies, win World Cups and Grand Prixs, and you can compete with other real people over the Internet.
But, erm, yeah, I play computer games a lot. Maybe too much. MMOs are the worst of all, so stay away from those, Jenkinsbball!
Try Company of Heroes. Yeah, it's a strategy game, BUT it's very different from stuff like Command & Conquer or Warcraft. In the singleplayer campaign, you mostly just command a small number of squads, and there's hardly any base-building. I've heard of many players who dislike traditional RTS games, but really dig CoH. So give it a shot.
Oh, have you played Deus Ex (1)? It's much better than 2. (Unless you play games for the visuals rather than the game).