Save your nation from destruction by completing a series of defense missions. Strategically build towers to eliminate waves of enemy soldiers before they destroy your castle. As you progress, new towers become available for you to build.
Aliens have landed and want to eat the farmers' brains! You must defend the barn. Strategically arrange the crop circles to make them follow a path of your choice. Then place your military assets and blast them back to space!
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.