Take control of the Stone Age general, scout out your enemy, find their weakness, gather your soldiers, and march on the enemy village. Victory will require total annihilation of the enemy faction; leave no one and nothing alive.
Defend your fortress from the oncoming enemy waves. Place turrets in locations of your choice on your fortress, creating the best defense possible to withhold even the greatest of attacks.
Eliminate the invading force intent on taking Space Station Xorbe in Earth's orbit. If the station is captured then it'll become a staging ground for the invasion of Earth itself. You got a huge arsenal of weapons and defensive mechanisms to stop them.