The game controls like a regular shoot-'em-up: and shoot bullets, drops bombs; there is rapidfire. However, unlike regular shoot-'em-ups where weapons are upgraded through powerups, your ship "evolves" to survive situations and get past obstacles.
Evolution occurs with the Evol (small faces with an E on them) and B-Evol (darker Evols). Each pickup adds a new evolution state to the list. After a particular amount of time, one evolution wears off and the next evolution is chosen. The DNA powerup does provide a more permanent weapon upgrade, but will merely just make the existing weapons stronger. You can hold up to nine DNA powerups.