Use WASD to move and your mouse to buy and place towers. Select a tower from the menu on the right, then click on the green area, near yourself, to place it. When you have your towers placed, press Start to summon the robot invaders!

During combat, move around to dodge bullets. You can also push robots by clicking to swing your wrench. When the robots explode, they drop shrapnel, which you can pick up by moving near it. This is what you use to build new towers, so make sure to grab it!

Keep building new towers to hold off the robot army for 20 waves!