Give every galaxy a massive wormhole that leads to another galaxy, It would be placed at the center of the galaxy. The wormholes would require players to fly directly into them rather than get sucked in, Meaning a faction could construct defenses around a wormhole to destroy any invaders, Effectively blockading the galaxy unless you go the long way.
I like the idea of wormholes. I don't like the idea of there only being one at the center of the galaxy. I can see a wormhole being much like a black hole, except easier to use, and I would like that.
Here are some of my own ideas to throw out there:
-Perhaps wormholes could be unstable, with the entrance and exit moving periodically or collapsing. They could be stabilized by having an astrotech beam firing at it.
-Wormholes would come in different sizes, some having a 20 radius, others having a 500 block radius. The entrances and exits would always be the same size.
-Wormholes would always have 1 entrance and 1 exit.
-When a player flies through a wormhole, they are not instantly transported, but rather enter a strange dimension. The player has to move from one side to the other to come out the other way. It would perhaps be the length of one sector. There may be strange, ethereal types of resources here. Or there may be hostile aliens.