Donkey Kong Jr. - Retro Gameplay

The original Donkey Kong had its barrels and whatnot, but its mechanics probably defined Mario better than DK. Its 1982 sequel, however, was probably the most fun of the ape's three first games, and also defined the real foundations of the character and the franchise: vines, bananas, jungle environments, jumpers, platforms... and Mario being the bad guy. Well, that last point isn't exactly defining, but interesting nonetheless. Take that, silly plumber!