In the future, the eyes of all humans leave their bodies and fly to the moon, develop weapons, and attack the human race, capturing several Asian countries, including China, Thailand, and Korea. Humanity sends two blinded pilot brothers, Mickey R. Dole and Mackey I. Dole, who both possess a sixth sense, to defeat the invaders. Each pilot's custom fighter uses a different attacking technique.
The gameplay of Clean Asia! progresses as a vertical shooter. Backgrounds are completely black, with enemies and the player appearing as outlines. Bright neon colors are used, giving the game a hypnotic atmosphere. The two ships, known as the Attractor and Reflector, have different gameplay styles. The Attractor is the most unconventional, possessing no weapons, and attacking by ramming enemies and shooting fragments at other enemies. The Reflector is more traditional, with regular weapons. The gun of the Reflector can be charged, causing the player's fighter to stop moving, and can also be upgraded by collecting 100 pieces of enemy debris. This debris can also give the player shields and bombs.
Clean Asia was started as a 2007 competition entry at shmup-dev.com. The competition's criteria were that the game had to be a shoot 'em up, and include an autofire function. The game was developed using Game Maker, while the music was licensed from another composer. It later won the prize of $200. Söderström tried to be as original as possible when designing the game, drawing inspiration from the ability to pick up enemy debris in 'Nvaders, a game which he thought felt "slightly rushed" and "incomplete". He was also inspired by another, unnamed shoot 'em up, in which the player is able to use an enemy's weapons against them. Söderström believes that the game's most creative aspect is the gameplay of the Attractor. Clean Asia! was developed during the span of two months, with most content being created in the last few weeks.