Mario Bros. was created by Shigeru Miyamoto and Gunpei Yokoi, two of the lead developers for the video game Donkey Kong. In Donkey Kong, Mario dies if he falls too far. Yokoi suggested to Miyamoto that he should be able to fall from any height, which Miyamoto was not sure of, thinking that it would make it "not much of a game. " He eventually agreed, thinking it would be okay for him to have some superhuman abilities. He designed a prototype that had Mario "jumping and bouncing around", which he was satisfied with. The element of combating enemies from below was introduced after Yokoi suggested it, observing that it would work since there were multiple floors. However, it proved to be too easy to eliminate enemies this way, which the developers fixed by requiring players to touch the enemies after they've been flipped to defeat them. This was also how they introduced the turtle as an enemy, which they conceived as an enemy that could only be hit from below. Because of Mario's appearance in Donkey Kong with overalls, a hat, and a thick moustache, Shigeru Miyamoto thought that he should be a plumber as opposed to a carpenter, and designed this game to reflect that. Another contributing factor was the game's setting: it was a large network of giant pipes, so they felt a change in occupation was necessary for him.