The humans are at war with the Filune alien race. Unfortunately they have the better cards, but humanity has one last ace in its sleeve: a powerful mech. The player takes control over its pilot Roy Becket to throw back the aliens. The story, which is told in both anime cutscenes and chatter during gameplay, also features additional characters like two girls Fiona and Estina scarred by Filune experiments and Roy's adoptive father Grato.
Astebreed is a scrolling shooter without a fixed perspective: during the six levels, the perspective shifts dynamically between side-scrolling, top-down and a behind view. The mech has three basic attacks, all with two sub-variants: regular shots, homing attacks and melee attacks with the blade. Additionally there are three powerful EX-attacks available which can only be activated when the yellow bar (automatically refills over time) is full. The player only has one life (plus continues), but the mech has a replenishing shield which can take a certain amount of damage. The achieved high-score depends on multiple factors, most importantly the tension meter (basically a multiplier) and shield bonuses for avoiding damage.
The PlayStation 4 version Astebreed features improved graphic effects and a new game mode called Arrange. The control system has been updated to allow the mech to lock on to enemies and controls can be customized. A different ending movie is also included, along with a few minor changes such as removed profanity and adjusted trophy requirements.