My friends and I came up with a new option for those who suffer from players who don't like them attacking other players (ie., husband on wife fighting). We came up with a pirate race. Here's the rules:
After the universe is built, find the system with the highest Resource and replace with a random race (chosen after all players already have their races) system tile. Look at the race card for them and place starting units on their home planet (if multiple planets, randomly determine). The Pirates always go last in the round (ie., Strategy #9). Whoever is the speaker, takes the Pirates turn.
1) Roll a d10/2. This is the max number of "pieces" to build at a pirate owned space dock. You have 6 resources with which to build (no matter what the planet/space dock does - since the pirates can't get tech, that seemed the fairest option). The speaker gets to choose which space dock to build at, if the pirates have more than 1 dock out.
2) All pirate ships in a system move as one fleet. Any ships that end up landing in a system with other Pirate ships automatically become part of that fleet and stop moving (we usually start with the smallest fleet). The pirates have no fleet size restrictions. All pirate ships ignore red bordered tiles, they can freely move into, out of or stop in any tile. The Pirates also do not activate any Domain tokens or bother any neutral planets. There is a 50/50 chance that a Pirate fleet will use wormhole (if they are in the wormhole nexus, they randomly go through a wormhole).
3) The speaker rolls a d6 to determine the direction the fleet moves (we originally had a rule that they would move automatically to an adjacent tile if there was a player there, but when one of our players had a War Sun parked on the tile adjacent to the Pirate home world, the pirates didn't stand a chance).
4) The Pirate fleet moves as fast as the slowest vessel in the fleet. If the whole fleet can move more than 1 tile, they roll their direction on each tile they land in.
5) If the Pirates land in a system with a player or a player owned planet, they will attack. If they attack a player owned planet, the fleet will drop all their fighters/ground forces/mech units on that planet. On their next turn, the Pirates will build a space dock on that planet. If all the Pirates space docks are already out, the fleet will leave the units on that plant and take as direct a route as possible to their nearest space dock to resupply the fleet.
6) Pirate ships and planets count as "enemies" or "players" for any cards, strategies or objectives.
7) If a player wipes out the Pirates home planet (typically for an objective), that player must move their ships out of the Pirate's home system on their next turn. The turn after that, place a free space dock on the Pirate home world and begin building again.
I believe that covered everything. We played once so far with this and it was great fun. The husbands finally got to blow things up. Have fun pirate hunting!