The Guardian Gamesblog kicked off a great discussion on their site, talking about games that just keep pulling you back in. Games that, even if you've played through them once, you just have to pick them up again. eToyChest and Kotaku both have related threads. So, what about you? What are some videogames that, even years later, you just have to play through one more time?For me, besides my ongoing fascination with World of Warcraft, Star Wars Galaxies, and Everquest II, there aren't that many that needed more than one playthrough. Both Half-Life titles, of course. I needed to play HL2 just to get everything I missed the first time. Jedi Academy and System Shock 2 required additional plays to try the game at a different angle. Similarly, I've played through the Diablo titles more than once each, as there's just so much clicking to be had. I somehow managed to avoid the gravity well of Civ4 for the most part, but Civilization 3 was almost the only game I played in college. Good times.