The gameplay will mostly focus on intrigue and conspiracy. So the players are supposed to be members of a secret society/cult/roleplaying community/guild/masonic lodge. This makes motivation easier - e.g., the Only True Eastern Boleslavian Lodge trying to get hold of alien weaponry to defeat their enemies, the One Unreplacable Eastern Boleslavian Lodge, and so on... I'll include a few sample societies in the sourcebook, also possibly sample characters and maybe a scenario/conflict outline.
I'm thinking about adding an optional "secret agenda" feature. During character generation and background-write-up each player choses two agendas. One they are openly pursuing (openly to the other characters) and one "dark secret". Maybe not all of them, but, say, 1 outa 3 players, or 2 outa 5.
So really, the alien thing is part of the background flavour. The interesting stuff is the cult/orders the characters are members of? I like the idea of searching for "alien weaponry". It'd be kinda cool if the alien tech sometimes acted in a "magic way" so that groups created rituals around the tech.