This game is as simple as "choose Red", but the challenge is the super-short time limit. Choose within seconds (or less), or the game is over. As you play more, the time limit gets shorter and shorter as you level up. You also get challenged with more and more images to test yourself against. It might be easy to tell the difference between red and blue, but how quickly can you tell the difference between salt and pepper?
Great game for short waits, because you will lose quickly, maybe you will last a minute if you're good.