However, I started to think of an adventure in a 'megadungeon' sort of environment. My first thought was a temple on a distant world with deep passages beneath, but that basically is just a regular megadungeon. This one should be more 'space' themed. I googled this and pretty quickly came upon a thread where someone talked about Moria on the Death Star, and that did it for me.
That's quite the elevator pitch.
The basic idea comes from my idea for the Citadel of Tomorrow in Doc Stalwart's world - it's a massive research center that had something go cataclysmically wrong. If this space station has been floating around for two hundred years collecting all sorts of crazy stuff from hundreds of worlds, then there's a clear in-game reason to have a wide range of encounters. If this is a just a ship from one race where something infected them (the bad guys got a fungus that made them all zombies), you have a pretty good environment. But... if the peaceful scientific folk were infested with that fungus, and the infected started opening all of the cages, and the uninfected survivors have quarantined themselves in an area where they are clinging to survival and their sanity, and a thousand strange creatures are roaming the halls... that sounds like a megadungeon. Throw in a few dozen MacGuffins they have collected over time, and this begins to work like a Megadungeon.
Sure, you can go in and try to explore the whole thing (good luck, kid), or you can enter airlock 47, traverse the third level concourse that has been overrun with spider-creatures from Alax, bypass the security systems for the vault, overcome the summoned void creatures that are also trying to get this item, recover it, and fight your way back out. This sounds more mega-dungeony to me.
It also allows me to create a 'monster manual' at the same time that details the various creatures throughout the planets of the Pale.
I'm going to need a spreadsheet to keep track of all of this. Sounds fun!