Savage Moon is a tower defense strategy game that pits the player (who is trying to mine valuable minerals from sentient asteroids or Imoons,) against massive chitinous, armored bugs called 'Insectocytes'. As the humans burrow into the ground, the Imoon produces its own auto-immune response in much the same way that the human body produces white-blood cells in response to an infection; this is when the killing starts!

This PSP entry in the strategy franchise focuses on the Hera Cluster. Preliminary intelligence suggests that it consists of 20 Imoons populated by a rich variety of Insectocyte forms, some of which have been encountered before and some of which are new. To combat the bugs, you have a new Sniper Tower at your disposal, and now have separate drop-pods (that land a new combat or support tower) and block-pods (that land a blocking tower) for defense. More importantly, you now stand as the Supreme Commander of the entire armada, controlling events for the whole campaign as well as each individual Imoon mission. The player chooses which Imoon to concentrate their resources of drop-pods, block-pods and credits into via the new Tactical Layer interface. Success on a mission results in more resources and the unlocking of new technologies.