BioShock 2 definitely tops my list, the entire thing just felt half-assed and desperate. Plus even though i liked it more than any Batman item aside from The Dark Knight, the Arkham Batman video games i know won't ever be part of the DC canon. Not that it matters, the DC canon is fucked up beyond all repair even after the relaunch/Flashpoint whatever.
And lastly i don't consider Assassin's Creed: Altair's Chronicles to be canon.
And lastly i don't consider Assassin's Creed: Altair's Chronicles to be canon.