My most played game according to the stats page, is Modern Warfare 2 with 48 day on record. That equates to spent air package glitching, model duel wielding, unlimited ammo shooting, dumb 12th prestige lobbing, buddy boosting. That game had so many things wrong with it but is still played the crap out of multiplayer. The game was best when it was broken.
Though as a child i did not have a perception but i probably spent 1,000's of Hours playing Pokemon, Gold Version.