The Space Marine Mammal is a limited edition character playbook for Apocalypse World. It also includes Supplemental: Walking Suit From the introduction: 50 years ago, the enemies of Earth unleashed a psychic weapon that destroyed all hope for the future of dolphinity. Anticipating the attack and its outcome, leaving many behind to suffer and die, your grandparents rushed to evacuate Earth. They built secret orbital stations and expanded the hidden Mars base into a functional colony. Their grandchildren - you - are all that remains of true dolphinity after this appalling apocalyptic assault.