[Trachmyr]

first and foremost: If you have faster ships and you use your head, you can always evade your opponet to the 30 turn limit... (providing you don't enter at a worm hole and get immediately bLasted by long range weapons).

So the easiest way to allow (easier)retreat is simple... don't have any map borders.

In order to balance this, supplies should be used for movement during combat... thus if you keep on retreating you'll eventually run out of fuel and be caught.