Alien Soldier is a gripping action game where you play as Epsilon-Eagle, a former leader turned enemy. The game takes place in a world where mutants, once led by Epsilon-Eagle, now follow the evil Xi-Tiger's orders.
The gameplay begins with choosing four out of six weapons, each with its own strengths and weaknesses against specific enemies. As Epsilon-Eagle, you also possess unique abilities like teleportation and shape-shifting into a powerful phoenix.
With 25 levels to complete, the game features short side-scrolling sections and challenging boss battles that make up the majority of the gameplay. The side-scrolling segments are designed to allow players to collect ammo boxes, while bosses require strategy to exploit their patterns and weaknesses.