10. Donkey Kong
It started out as a popular arcade game, daring gamers to avoid flaming barrels and help a tiny Italian caricature rescue a princess from a ginourmous gorilla. But once designer Shigeru Miyamoto's creation was adapted for Game & Watches, the curious portable devices that were the precursors to PSPs and made Nintendo a gaming behemoth. . .oh, then it was on. The game not only gave birth to the company's primary cash cow — the Super Mario juggernaut starts here — but would prove to be as innovative (it was one of the earliest platform games) as it was difficult to beat. To this day, there aren't many people who can complete the entire game. . .which hasn't stopped millions trying.