I'm having fun playing 2-player co-op games with the base box. You can use the enemy flowchart from the solo rules, but otherwise play using the standard rules, just taking turns between the (automated) enemy and your two players. You can either split the clay and gems or work together with one army. The rules are still balanced. I wish there were a little more to it, but I'm excited to try the expansion set. I wish the makers would share co-op rules for friends to play together non-competi...