In Battlantis, players take control of Cripeuss III and attempt to defeat Asmodeus and the monsters invading his castle. Enemy formations are similar to those in Space Invaders and Galaga, with some monsters charging to the bottom of the screen. Occasionally, two monsters carrying an ark will cross the screen. Shooting this ark will drop a powerup, temporarily giving a more powerful shot. Once enemies reach the bottom, they fly sideways towards Cripeus III, making them nearly impossible to defeat unless the player has captured two power up, allowing sideways firing.