I'll get my normal flack for this, but I'd have to say Final Fantasy XIII. Hardly even counts as a game. it's an RPG on rails without so much as the common courtesy to give you a good, well told story with even remotely likable characters.
Duke Nukem forever was pretty bad, too. At least it was functional, even if it was insonsistent, boring, unfunny, and annoying.
Another one of my worst games was Bloodforge. Just broken. Nigh-impossible boss fight kept me from carrying on, visuals were muddy, story was derivative. just blech.
Another controversial choice is Soul Sacrifice. Complete disconnect of story and gameplay, bland, shallow, repetitive grinding, terrible graphics two generations behind where it should be...but admittedly great writing.
My Console Library:
PS5, Switch, XSX
PS4, PS3, PS2, PS1, WiiU, Wii, GCN, N64 SNES, XBO, 360
3DS, DS, GBA, Vita, PSP, Android