Memory Challenge

This is a card match game. The aim is to help improving memory. It's also challenging.
There are 5 level, from easy to hard:
1) Basic and try limit
2) Time limit
3) Shadow and mirror
4) Random match
5) Flash
In each level, there are sub levels of different color: green, blue, red. When you finish all the green and blue sub levels, you can move to the next level. You can challenge yourself the red sub levels, but they are very difficult!