Pirates, Marauders, Smugglers (A possible SEV Suggestion).

[psimancer]

try this on for size

marauders and other such appear form unknown space

say you make the galactic map capable of hiding systems

then add a new science "astronomy"
and a new component "stellar cartographer"
it would have a range like wrp point openers do
then it becomes a truely interesting game as everything is actually hidden and some systems like those darn nebula systems can actually have planets and such but cant be mapped until you find a warp point into them or you get high enough sensors with your cartographers/astronomers thus you can have hidden systems and wormholes and your marauders / pirtates can actually have bases or base ships or planets to operate from

and an even more fun item is to create the ability to interface one game to another with a galaxy gate that allows the movement from one game map to another that would trulyy make an interesting situation as you have your galaxy penetrated by another super empire (somebody elses save game ) at a random location