Door Door[a] is a 1983 single-screen platform video game developed and published by Enix in Japan. Originally released for the NEC PC-8801, it was ported to a number of other platforms, including the Family Computer. Controlling a small character named Chun, the player is tasked with completing each stage by trapping different kinds of aliens behind sliding doors. Chun can jump over the aliens and climb ladders, and must also avoid obstacles such as large nails and bombs.
Door Door was designed by Koichi Nakamura, known as the creator of Dragon Quest, as part of a programming contest held by Enix in the early 1980s. Winning first prize, Enix was given the rights to the game and ported the game to several Japanese home computers. Chun, the name of the protagonist, was a nickname given to Nakamura by one of his friends. Door Door was a critical and commercial success— the PC-8801 port alone had sold 200,000 copies, and is considered a classic title for the Famicom.[
Source: Wikipedia, "[en.wikipedia.org/wiki/Door_Door Door Door]", available under the CC-BY-SA License.