Of course, I'm going with Kingdom Hearts here. Jet Force Gemini was innovative for it's time. It mixed elements of platforming, action/adventure, and shoot em ups and created a very unique game. Although the sales didn't reflect that, it's still revered as one of the best N64 games of all time. However, Kingdom Hearts, I will argue was even more innovative. From creating a story with characters of Final Fantasy and Disney involved to the gameplay of using the keyblade and magic to defeat the various Heartless, there never was a game like Kingdom Hearts before it came out. It eventually became known as one of the best PS2 games of all time and created a new, productive series for a company that was fixated on one game, Final Fantasy. You can't go wrong with either vote but if you could just vote for Kingdom Hearts.