Literaly what the title says. Personaly, I love all the races we have now, but there needs to be more variety. Just post what new alien race you might want. I would like a parasitic like race that is similar to the flood in the Halo series. But there is a catch. Nobody can play as them. Instead, they would be operated by a super hard AI. They wouldn't show up at first in the game, but after discovering some type of artifact on some planet, instead of it giving you advantages, it would unleash the race. At first they would be nothing but a nuisance, but after a while if they are winning battles and completely destroying enemey fleets, they would take over the ships and start building up a fleet until they are ready to attack again. Depending on the number of ships they have, they might only attack smaller targets until they have more ships. They would not be in the diplomacy, they would simply try to kill you. To make it seem more interesting, you could make the ships strange looking, such as having some type of growth on the ships and all ships not having as powerful hull points or shields or weapons. Planets they capture would give them a boost and they would get a large amount of reinforcements from the planets or something like that. To take the planet back, you would have to destroy everything that is on there(15000 or something) Essentialy, these would be like  super pirates, but if they are not eliminated early, they become a huge threat that could quite concievably kill everybody in the game if not eliminated. I can't consider all the specifics and only gave a few situations, but it should be similar to the flood in halo and them being able to infect every type of ships. I have no idea how to do this and it may be too complex to work out, but I don't know all the specifics. I just know this race would make the game a whole lot more interesting if the programmers at stardock can pull it off