Dif. - Find different letters shapes and pictures

A game that need players to find the unmatched element in the matrix or annulus.
Two modes:
Classcal mode:
Test your eyesight.
Exercise your brain.
Differences in your eyes
Time mode:
Finite time.
Infinite challenge.
As much as possible to find different.

Three different:
The number and letter
Difference come from the lack of a stroke
Color blocks
All same? No,different
Shape
I am a circle.You are a square.Let me out!!!
Enjoy!!!