Up to 10 players can play in a randomly generated galaxy with any number of teams. A balanced co-op game would be 5 players vs 5 AI. Technically you can't drop in, but you can drop out at any time and have the AI take over. Players can work together to conquer enemy AI, utilizing interface tools for communication and collaboration.
The time of Diplomacy is over. The length of the war and differing opinions on what should be done to bring the war to an end has led to a splintering of the groups involved. The controlling powers-that-be have depleted arsenals and seemed to have exhausted all efforts of diplomacy. Trapped in a stalemate, sub-factions have rebelled and broken off the main alignments. Rebellion is upon us.More Info @ PCGamingWiki