A mapper hack is a game ported from one board (that is stored inside the cartridge and that contains all the game's data) to another, more simple and easier to reproduce. This feature is somewhat well-known among the romhacking community, although, in order to save spendings, pirates also exploit this feature. In certain cases, this results in the final result being drastically butchered compared to the original. Mapper hacks are also often made to work on new bootleg reproduction cartridges or multicarts. In the case of official games, these are usually converted from MMC1 to MMC3 because the former mapper doesn't work on most multicarts.