Action 52 (NES): 52 games that are barely playable and most of them contain many glitches.
Sonic the Hedgehog Genesis (GBA): When you get outdone by an unofficial port, you know you screwed up. Glitches, poor porting of a soundtrack and it adds glitches not seen in the original Sonic the Hedgehog game!
Advanced Dungeons and Dragons - Heroes of the Lance (NES): By far the worst RPG out there. Who knew that one party member was required for the final boss and if she died, the game was outright unwinnable? Laggy controls, uninspiring gameplay, suspect platforming and it's another case of why licensed games back then didn't pan out, for the most part.