Worst game I've played on PS3 is Blacksite: Area 51. The game has no sprint button, the morale system is basically an excuse for your squadmates to not do anything when you do nothing, one button order system doesn't equal Ghost Recon or Rainbow Six. The game is too short and too easy, the protagonist is a Gordon Freeman wannabe, the other characters (except the black guy, name's Mitchell) who die basically do something stupid for that to happen (the guy in the beginning (Logan) should have stopped shooting aliens like Rambo and be with his wounded teammate), the segment where you have to shoot the cockpit of the helicopter with a sniper rifle is basically dumb (even if you miss the pilot, it doesn't matter). When you shoot down the helicopter, it'll always hit the screen at the drive-in theatre, the game trailers were very misleading (the TV ad was even misleading), I expected like an apocalyptic setting with buildings destroyed and car wrecks all over the place but the only waste I see is junk on the ground and the controls of driving a car are not basic (instead of pressing a button to accelerate and decelerate, you have to entirely use the Left Analog Stick). The only other games on PS3 that beat this are movie-based video games and Brink.
Worst game I've played on PC is Sniper: Ghost Warrior. I get seen while hiding in a bush while proning, nobody plays multiplayer (I don't know how bad it is since I got it when no one was playing multiplayer), the aiming when using the M4 is garbage (it's like my sensitivity was 100,000,000 more than what I toggled), the story was rather cliched (kill dictator of country = WIN). The instruction manual only has biographies of the protagonist and antagonist (I would rather have bios for all major characters or none), there weren't many cool parts to the game (the only one was the squad walking as something blew up far behind them) and the ENDING! The ending? Yes, the ending! No, wait, there is no ending! It's just "THE END", then the credits roll. I'd rather replace the last mission with a very long and detailed epilogue. End of story!