Gah. Actually there's loads of games that I've almost finished but just stopped.
Superstar Saga, Golden Sun 2, Pokemon Pearl, Metroid Prime Hunters, Metroid Prime 3, Advance Wars (ALL!), FF7, Tales of Eternia, LocoRoco 2, Star Ocean, GTA (all!), Super Metroid, Mario Galaxy, Brawl. This is becoming a problem
I never beat the final boss in superstar saga. I spent the entire game thinking you could only upgrade HP when you leveled up. Even with infinite everything I can't beat it because your health goes down to one in the last part of the battle.