Thank you so much for playing and for your kind words! The "green paint" has to be drawn on top of the "blue paint"... Once you purchase the secondary color upgrade. it gives you some green patches to expand with the familiar click and drag motion, but you have to have plenty or primary/blue paint already down to be able to add your green paint! Our game has some mechanics that are hard to intuit on the first play through and this is something we'd love to continue to improve! Glad you enjoyed checking out our game, thanks again!