Sky Soldiers is a vertical scrolling shoot 'em up in which you control one or two special space fighters called Stealth who must shoot air-based enemies in different time-zones.
It is 2090 and mankind has developed a supercomputer called Desmoura. It achieves sentience as it sets itself around Earth's orbit. It becomes so powerful that it builds a time machine to send various war machines back in time to possible change Earth's history. Stealth space fighters are sent back to correct the time-lines and eventually destroy Desmoura.
There are eight time-lines to negotiate: Great Britain 1945, Germany 1915, Japan 1945, Germany 1944, Vietnam 1974, France 1914, Russia 1974 and finally the space station in the present time
Upon starting a level you are given a choice of four different special weapons to accompany your standard cannon. Each special weapon has a specific blast radius and a different supply of ammo.
During a level you can shoot specific airplanes who then leave behind crates that provide extra ammo or increase your bullets.
Each level ends with a a boss typical for the time-line which must be defeated.