I really have to agree with you on this one. I loaded HL2 on my computer the other day. I try not to play video games much and I figured HL2 and CSS could be played much less than, say, an in-depth MMORPG.
Well, scratch that idea, I've been playing it like mad the past week. I might as well be playing WoW which I didn't install yet because "i dont have the time during finals"....riiight.
I'm not sure why it's addicting though. Lots of games are considered addicting because they require time to level (EQ, WOW, D2, etc.) but CS doesn't require time... Maybe it's the fact that the games go so quick and that there's always people playing. I personally make sure the time is at least a little well-spent by talking during gameplay in hopes to find cool people to enjoy the time with.
-T