The Ancient Terrans are a key part of Frozen Skies' background, primarily for the setting's history and as a source of adventure hooks. There is also the chance for players to actually meet some Ancient Terrans, known as 'Lurkers', though admittedly probably not in a friendly manner. Since the last post about them, I've had a few more thoughts regarding them.
Old Masters of Technology
One of the biggest things that the Ancient Terrans had going for them was their technology, some of it has been retrieved by modern Darmonicans like the Skyships have others are still far in advance of anything currently seen. Its plausible that the Lurkers would still use some of this old technology, least the devices that they can keep working since making new ones would be a tad...difficult.
One thought along this line is having the Lurkers' Life Drain ability actually be some sort of device, a sort of personal life replenisher that works by stealing another person's life essence. This can extend to other devices such as one that cloaks a Lurker in shadows and thus allow them to sneak up on somebody unaware, perhaps even some sort of holographic device to help unnerve and dis-ordinate potential...erm...'food'.
Lots of possible ideas to run with, plus it ties into the Weird Science Arcane Background that is already in the setting. Still running with the idea of 'futuristic' weapons such as raygun style laser weapons.