It might be best to plan for a 2 on 1 style battle unless someone else shows up. We could pretty easily plan on maybe 2000 points per side, or 1500. I'll probably bring a little of everything so we don't need to decide the sides just yet. I don't have any land units, I'm not sure if the Martians work in the ocean.
A free for all could be interesting but we would need to make it very objective based to minimize the gang up situation.
Do I need to call them and let them know we are planning on being there?