Game: Final Fantasy (1987)
The original Final Fantasy created so many of the things that would become long-running tropes of the franchise. Airships, black wizards and, heck, even leveling up. One of the major plot points of the original FF was to have your party transform, sprites and all, from newbs to battle-ready warriors. This was a pretty big deal back in 1987, especially for teems of twelve year old boys who were undergoing their own, ahem, transformation. Final Fantasy IV gave a brilliant nod to this scene with Cecil's upgrade to Paladin toward the end of that game.