Ya, two player would be nice! or missions or soemthing. this game is really fun but gets old : P, eventually it's just like, "Oh tons of zombies, oh well my turrets will pwn them." Good game aside from the getting old part.
great game, could use more multiplayer support. maybe a duel sector, where you organize duels with people or some kind of gang adventure sector, where you can only see people in your gang and do missions with them or something. For example, there would be a mission type "gang" and it would read something like this: Go to sector "-" (gang sector) and await further instructions: 2054 for each player.