In the game Guess My RBG, you are challenged to find the RGB color value of the background by adjusting the red, green, and blue sliders until you are correct. You will not get it right on the first try, but you can use your incorrect guesses to get closer until you hit the mark. Each incorrect guess will display in the color you guessed, and also tell you how close you are.
The difficulty comes from the fact that these are the colors of light, and I am more familiar with the color values of paint. Where is the yellow slider? It doesn't exist in the RGB model. Also, when you get close, it may be hard to distinguish the guessed color from the target color, depending on the functionality of your eyesight. And the previous game will affect your perception. Once I loaded a new game, and thought, "That's blue!" But by the time I made a few guesses, it became clear that the background was gray. Still, practice makes perfect. Try it yourself! -via Metafilter