Think you have good eyes? Prove it with this addicting game! Simply tap on the square that is different from all of the rest. It gets harder as you go.
How many shaded squares can you find in 30 seconds? Mistakes don't count against you in Easy mode. But, make a mistake in Normal mode, or take too long to find the square, and the game ends. Unforgiving mode builds on Normal mode, but disables the gradual fade of the grid lines to help you out.
You can also try for time in the Sprint mode to see how fast you can find 25 squares.