How Good is Your Color vision? KukuKube App Tests your Ability to See Subtle Differences in Shade

KukuKube was created by Canada-based Network365. The free app is available on Facebook, Android, iOS and on desktop browsers and starts with four squares on a gameboard. I

t asks players to identify the square which has a slightly different shade to the rest and as the board grows to 81 squares, the differentiation becomes more subtle each time. 

A score of 31 or above is a sign of 'great eyesight' but the app should not be used to replace official eye tests.