Armored Core for Answer and Monster Hunter. Both pet franchises of mine that no-one else cares about. Every other game, including the likes of Skyrim, Black Ops and Battlefield: Bad Company 2, has occupied me for as long as it took to complete it to a satisfactory extent (except Skyrim, the f***ing reunite Skyrim quest broke and I was like "The White Phial and that orc's books I can deal with, but f*** this s***, this is meant to be one of the main things to do in the game). This meant about 5 or 6 characters in Mass Effect 2, 3 playthroughs of MGS4 (an IhavenoideawhatI'mdoing run, a no-kill no-alert run, and a lulz run to enjoy all the awesome stuff I got from my last run) and 2 playthroughs of Deus Ex: Human Revolution. But it is rare that I will actually revisit a game, I often sell them on for the next game, but these two manage to induce multiple phases of mania, god knows how.
Or maybe it's just because FROMSoftware hasn't made another Armored Core in ages and MH moved to the f***ing DS. Damn you CAPCOOOOOOOOOOOOOOOOOOOOOOOMMMMMMMMMMMMMMMMMMMMMM!!!!!!!!!!!!!!!!!!!!!!!
P.S. Yes ACV is almost out, so maybe not so much the first one.