It struck me while playing through a bunch of other old platformers that the way Mario runs with the B button and gradually accelerates was seldom replicated. Most games used the B button for a weapon of some sort, and the player character moved at one consistent speed. It was probably hard to program the way that speed could change the distance of jumps and such, but a game did eventually focus on copying this aspect of Mario with Sonic the Hedgehog, making the acceleration innate rather than requiring the player to hold down a button. Sonic happened to become Mario's biggest competitor. Maybe Go Fast is a more universally appealing idea than Kill Stuff.