Fun game and innovative use of the limitation! Having both the left and right mouse buttons to switch colours and having another key like space bar to shoot would be an improvement over the current control scheme though, since now it can take 2 switches to get the correct colour. The spawn patterns also make it really easy to get enemies into one big clump and circle around them without ever taking damage. Really great game though, would love to see it expanded! Maybe with enemies that can fire projectiles?