Leaderboard

GIMP -> Select target layer -> Colours (top drop down menu) -> Hue-Saturation. From there you select common RGB values and change their hue, brightness, and saturation values. Be wary of overdoing saturation, colours lost are difficult to regain and therefore also difficult to alter. Other options in the 'Colours' drop down list are all also very useful but some take a lot more know-how to use right. I personally use nearly all of them, including the more complex ones like curves and levels. That stuff takes no explaining, but experience from trial and error. Believe it or not but creating a game level will actually help you figure these things out in natural pace, because in your head you will have a better idea of what you actually want, and that becomes your goal.

Happy birthday @OWA ! @Romanov has baked you a nice yummy cake. Please share with us @TeamWolf was too curious and opened your present already, sorry D: P.S. Siege Chopper is there because you like that unit, and Battle Fortress because why not. (You've modelled/finished all the units on your cake )