Another interesting thing to try is the merry-go-round map...
Take a spherical map like you have, and close all the half-warppoints leading up or to the left.
Now you'll have a spherical quadrant full of one-way warppoints so you can only travel right or down.
Enemy fleets will be pouring in from the top left, and the only way to counter-attack is to push down and right until you wrap around and hit the back side of your enemy's territory
