Mario is Missing.
When I was little I would get very excited whenever I got to play a new game, because it was kind of rare that I'd get new games. I remember one day we were at Blockbuster renting some movies (which we didn't really do that often) and my dad let me pick a game to rent too. I was super excited about this, and I looked around the NES games and found Mario is Missing.
For those of you unfamiliar with this game, it's basically a licensed geography edutainment title starring Luigi, who is looking for Mario. It's not very game-like at all; it's mostly just geography trivia with some very light platforming (if even). It wasn't made by Nintendo, and is from the era where Nintendo wasn't as protective of what their IP was associated with as they are now.
Basically what I'm saying is that Mario is Missing is a total piece of shit.
I didn't really know any of this going in. I just thought it was a new Mario game and I was good at Mario games so I wasted my rare chance in renting a game on it. I remember going home, popping it in, and being utterly confused, then angry, then disappointed. This was not a fun new Mario game with interesting worlds, power-ups, and enemies; it was a mean trick played by adults trying to fool kids into learning boring geography trivia.
The depth of my hatred for this game and everything it stands for cannot be overstated.