What about a "one-way" galaxy?
All the warp points are one way "to the right". The right-most systems wrap around to the left-most systems.
You wouldn't have to worry about the guy on your right atacking you, but you could attack him. You would be attacked by the guy on your left, but couldn't fight back!
It would be a galaxy-wide rock-paper scissors game, with the left side of empires crumbling, and expanding on the right.
You'd have to keep pressing the guys to your right harder than the guy on the left is hitting you!
Just disable stellar manip, and the empires will drift around and around and around the galaxy
.