Got a few of ideas in that direction,

One is simply to not allow players to visit planets owned by someone else in the team. Creates a good teamwork strategy here since it means you need you work out resources and co-operate on that front too. This would work great with massive maps where there is a bit of flexibility behind empty planets and such.

Another is like mean RTS games that have allies and have a passthing through feature; where the team mate has no control with your factory levels or ships, however just sits perched on the side happy to defend that planet from others until it moves on.

I'm figuring the idea behind the gameplay is to keep it as simple as possible (hence why there are only 3 possible controls!) so it's just a matter of how complex you want to make it.

Either way, keep up the great work!

Hi Dingo, awesome game you have here, we got a group in the office and we've come up with the idea of getting a couple of AI with a high intelligence and the group of us here versing them. True temporary alliances are good and then great fun to turn on each other, but how about a team option for a combined victory?