Door Door

Door Door is a Japanese-developed computer puzzle game designed by Koichi Nakamura and published by Enix. As Enix's début title, Door Door first released in February 1983 for the NEC PC-8801 and was subsequently converted for other Japanese computers. The game's success prompted a Famicom port and an expanded edition in 1985 and a mobile phone release in 2004. In 2006, editors of the popular Japanese gaming magazine Famitsu placed the game among classics such as Super Mario Bros. and Donkey Kong in its listing of the best Famicom games. Despite its popularity, Door Door has never been released outside of Japan.

Gameplay
Door Door is played through 50 levels with the goal of trapping aliens to score points. Each level consists of platforms and doors, with enemy aliens chasing you. The basic strategy is to open a door while an alien is following you so that it enters the room beyond, then close the door to trap your enemy. Doing so results in scoring points, and the amount of points increases with each alien you trap behind the same door. Once an alien has been trapped behind a door, it can no longer be opened.

You start the game with three lives, and you lose a life whenever an alien touches you, when you fall off a ledge or you touch a green spike. You gain lives by accumulating points. Besides trapping enemies, you can also gain points by picking up items. Every level has a place where the item is generated, but which item will be generated is randomly selected.

Player
As the player, you control Chun. Your goal is to trap every single enemy behind a door. Once you close a door behind an enemy, you can never open that door again. If a door possesses two doorknobs, then it can be opened from either direction. Otherwise Chun must approach the door from the side that possesses the doorknob in order for him to open it. Chun will lose a life if he ever collides with any of the enemies, or if he falls down a gap in the floor.

Namegon
Also nicknamed Kyoro Kyoro, Namegon is a slug that takes which ever path is best in order to chase Chun. While he is the most dangerous because he takes the most direct path, he is also the easiest to trap behind doors.

Invekun
Also nicknamed Biyo Biyo, Invekun is a jellyfish who is compelled to climb every set of stairs that he encounters. Even if going straight would get him closer to Chun, he will climb the stairs anyway.

Amechan
Also nicknamed Gucha Gucha, Amechan is a jelly that will usually climb every set of stairs that he encounters unless Chun is on the opposite of a set of stairs that he is considering. In this way, Amechan acts very similar to Namegon.

Otapyon
Also nicknamed Pyon Pyon, Otapyon is a tadpole that has the ability to jump whenever Chun jumps. Because of this, Otapyon can never be jumped over, and must be completely avoided.