A classic trope of speculative fiction, the Desert Planet is a One-Biome Planet set to Desert. It often comes with some sort of Hydraulic Empire - a form of despotism based on control of access to water.
This trope is old and well-respected, showing up in classics from Dune to Star Wars, despite the fact that it makes no damn sense. Just stop and think about it for a moment - without any forests, without any oceans full of algae, the planet should have no oxygen. Oh, maybe it had some by random luck of planetary formation, and that was enough when it was uninhabited - but stick a million colonists on the planet, and they'll asphyxiate.
Game and Story Use
- A smart GM comes up with some sort of explanation (even if it's just a hand-wave for why the planet has oxygen, and has this explanation prepared before the players ask. Don't get caught with your pants down.
- There may be some sort of oxygen-producing life form on the planet that just doesn't look like a tree. "Sand algae", maybe, or a really cool form of cactus.
- A precursor or sufficiently advanced civilization buried huge terraforming or oxygenating machines beneath the surface.
- The planet has only recently become a desert due to the end of the world as we know it, and it's just a matter of time before people start suffocating.
- Desert planets are good for playing with themes of isolation, remoteness, and the conflict of man vs nature. As such, they fit especially well into settings where travel between worlds is difficult.
- The shifting sands let you hide a lost city, artifact, or other macguffin beneath the surface. A big sandstorm can uncover or re-hide it as the plot demands.