Half-Life 2 was pretty long, I can't remember, but I think I put in over 10 hours on it. EP1 and EP2 are pretty short though. I wouldn't mod the game, it was perfect as is. The only games I have ever put in repeated 5+ hour sessions with. Hell, my little 5 year old niece stayed at my side and watched me beat the entire HL2+EP1+EP2, and she thought is was the coolest game ever. She loved the ant pheremone or whatever. "Throw a stink-bomb!" Not many kids can find something entertaining enough to keep them planted in their seats for hours at a time. In fact, I'd stop playing and she'd get upset and want me to keep going. And this might sound strange, but I didn't even like HL2 when it first came out, it took a few years, and a few tries, to finally get into it. But once I did, it to this day stands as one of the best PC gaming experience I have ever had.
Edited by Aaron_Henderson - 3/6/11 at 8:19am