Galaxy Defenders is a sci-fi cooperative, tactical battle game in which 1-5 players fight together against an oncoming alien menace. Each player takes control of one or more agents with unique powers to defend the planet from the alien invasion. Gameplay revolves around a tactical combat system, using custom ten-sided dice. Each player sequentially plays his Agent turn and then one Aliens turn. Players carry out their turns [agent and aliens] in clockwise order until the last player finishes his Aliens turn. Once done, the game passes to the Event phase that will bring the players to the next round.
The combination of a unique AI for each alien species and the uncertainty about alien activation in a turn provides a realistic simulation of the chaos of battle and a sophisticated challenge for the players. Since having more agents brings more alien activations for the aliens, the turn structure allows the level of difficulty to scale dynamically based on the number of agents in play. If agents die during the game, the system "recalibrates" the difficulty to a reasonable and enjoyable level, so you still have a chance to complete the mission.