In my opinion the best and most easy way for the tactical system would be just to copy the current MOO2 tac system, add a much larger tactical playing area (space is infinite) and add a bibliotheque of terrain and weapons effect graphics and let the players themselves mod in terrain effects on movement and weapons. Provide a space for up-and download of these mods online and I am sure this would please nearly everyone. Or the short version. let the crowd take part in it. I am sure you will be surprised of the creativity of some talented youngsters. Regarding using the whole solar system as playground I am not for it because it would change the tactical game to an operational game which is maybe nice to have someday but not in a MOO inspired game.