This insanely difficult color perception quiz is going nuts on Facebook

A free, insanely difficult color quiz is making the rounds on Facebook.

Called KukuKube, there are eight different levels that test your eyesight and give you a score. 11-15 is extremely bad, 15-20 is lower than normal, 21-30 is normal, and over 31 is amazing eyesight.

The online quiz tests your ability to differentiate shades of color. It starts out simple enough with four big squares and one shaded an obviously different hue:

Easy, right? Not for long.

It quickly evolves to groups of 9, 16, 25, 36, 49, 64, 81 squares while the quiz itself grows harder as it becomes increasingly challenging to pick out the shaded cube:

The key is to be quick, because if you wait too long, the game will end after 60 seconds and score you lower.

KukuKube gets easier the more you do it. The first time playing online, I got a measly 21, but after taking it again, I got 24, 29, and then an enviable 37.

And I'm not alone in wanting to share my score:

Find the different colored square (I got 26): http://t.co/QdBYj8RQ1N

- Lydia Choy (@choy) April 9, 2015

How good are you at differentiating colors? I am at 28. http://106.186.25.143/kuku-kube/en-3/

- Grant Davis (@BaronVonGrant) April 9, 2015

This is a lot harder than it looks :/ My highest score was 22 http://106.186.25.143/kuku-kube/en-3/ http://106.186.25.143/kuku-kube/en-3/

- AimForTheHead (@MamaLeysa) April 9, 2015

Kuku Kube http://t.co/LeJ69bwzIl <~ really cool game to see how good you are at spotting slight differences in color (my high score is 26)

- Hartley Brody (@hartleybrody) April 9, 2015

I scored 35 in kukukube, the world's most interesting eye test!! http://t.co/zOfQW43w4s #kukukube

- Ilya (@13xforever) April 9, 2015

For those who enjoy the web version, there's also an app for iOS and Android where the scoring and levels are a bit different, but no less fun.

You can play KukuKube here.