 Upon completion of the fourth stage, the level then increments, and the game repeats the stages with progressive difficulty. For example, Donkey Kong begins to hurl barrels faster and sometimes diagonally, and fireballs get speedier. The victory music alternates between levels 1 and 2. The 22nd level is colloquially known as the kill screen, due to an error in the game's programming that kills Mario after a few seconds, effectively ending the game.
