OMG, I just remembered two games which were way beyond bad, infact It's pretty safe to assume every gamer who has played them counts them as POS games.
Hydlide(damnit, I have a rep to uphold, one that states, I beat/destroy every RPG I play, so I kind've had no choice in the matter).
Then there's Dr. Jekyll, and Mr Hyde: Oh man boy does that game suck lol, but it being so annoyingly hard pissed me off to the point, that I had to keep trying until I beat it(I couldn't allow such a POS game to get the better of me. I hate that game so much, needless to say, after I beat it, I never touched the game ever again, as it probally ranks up there as one of the worst games of all time).