This post came to mind after I played the new MW3 campaign. For me personally it has to be Wolfenstein: Youngblood. That game was a complete disappointment compared to the rest of the new Wolfenstein games. The only reason I ended up finishing the game was because my friend and I were playing it together and decided to tough it out and see the end of the story. Gears of War: Judgement is another dishonorable mention. A game that I did not like at all, but continued to finish it solely because I had played every other game in the series so far.
Probably Heavy Nova for the Sega Genesis/Sega CD, and if you’ve never heard of Heavy Nova then Good. It’s a very terrible platformer-fighter hybrid with bizarre as hell decisions (crouching makes you invincible), terrible level design, and a default setting that makes you double tap backwards to turn around. Even if you turn the setting off your turn speed is molasses, it’s faster to jump (which ALSO makes you invisible).
If not that…Alex Kidd in the Enchanted Castle, then?