In this tower defense game, you can play up to 30 waves in campaign mode or unlimited in survival. Set up your towers strategically, but if they don't get the job done, you can take control of them yourself without a limited range by selecting a tower and pressing 'c'. At the end of the game, you're judged with a score by how well you defended your base and you can submit it to a leaderboard.
All the instructions you need are in the game, and at any time while playing, you can pause the game by pressing 'p'.