Co-Op will be available in a few forms. Comp stomp co-op is available in Arena Commander. Four player co-op ships will also be flyable in Crusader. The Squadron 42 campaign will features specific co-op missions outside of the main campaign
Star Citizen is an open world space combat game where players build and buy ships, trade goods, combat pirates, and play in arcade style arenas for fun. The game will feature FPS ground combat, co-op space ships, and a huge persistent open world. It's raised it's entire budget through crowd funding to the tune of over 50 million dollars.