SWG in the first year. WoW the 9 months I played it. FFXI was rather addicting as well.
Basically any MMO. They're designed to be addicting, life sucking, time devouring money burning tools of mental destruction. 
Person 1: Does Valkyria Chronicles have trophies?
Person 2: No.
Person 1: Forget it. I'm not buying it.
Person 2: Wait! It's amazing! Unique, charming, drop dead gorgeous... Hello?







