In the Galaxy Command rulebook, I mentioned that in the spirit of 70s sci-fi, players can re-skin baseline humans as human-like aliens. These re-skinned humans keep the human racial traits, but have the kind of minor physical alterations that a low budget TV show might use to create its aliens. These 'aliens' might just be human actors with elf ears glued to them, painted skin or fake pair of antennas added.
Spacecases takes this reskinning concept a few steps farther. You're not just building a one shot alien race for your campaign, you're building the bumbling kind of extraterrestrial comic relief that 70s and early 80s TV was known for. Spacecases makes use of tons of random trait charts. The goal of this sourcebook isn't a freeform humanoid alien creation systemrather you're building a fun to play sidekick from an alien culture you make up as you go along, and that is played mostly for laughs. The feats, racial abilities and cultural quirks are designed with screw-ball space comedy in mind.