System: Game Boy
The Legacy: The mobile gaming revolution was a grey brick, but a grey brick that changed everything. It was ultimately indistinguishable from the NES controller on the surface, which made it so patently approachable: In 1989, the idea of fitting the Nintendo controller and the game and the system was utterly futuristic, but at the same time, not at all intimidating: The same buttons made Mario run and jump on the Game Boy as they did on the NES.
That said, the Game Boy was still a moment for controllers: Instead of being set directly across from the D-Pad, the "A" and "B" buttons were offset to the upper-right side of the Game Boy, the way your thumbs naturally tilt up instead of to the side. From this point forward, all NES button layouts would be offset, and the controllers adapted that same curve on the side.