You are the last defense stopping a seemingly endless army of alien invaders. Build turrets to defeat the aliens before they reach your home planet and explode on it.
You can build and upgrade turrets by spending resources. You acquire more resources when destroying enemy ships. Building is restricted to the grid, but you can build your turrets in unique formations to lead the enemy ships on the a path of your choosing to deal with the threat.
There are 4 turret types: Gatling, Rail, Laser and Electro Magnetic Pulse. Each have unique properties and different uses. Click on a turret during the build phase (between waves) to see the stats. There are also useful tips displayed during waves. Survive as many waves as you can. The game is over when your home planet's health bar runs out.
Good luck, Commander! You're going to need it.