Memory Blocks - A game

A memory game in which a few blocks have objects with different colors hidden behind. Move the focus on to an object and press enter to uncover it. As soon as you move to another block this uncovered block gets covered. You have to uncover two blocks with same object hidden behind to clear both the blocks. This is a time based game. Faster the board is cleared the higher the points.

Snapshots:

Here is the source.

I frankly did not know this game was so engrossing and useful. I played it now and completely cleared the screen. I scored somewhere around 245 points. On special request of someone I have reduced the number of blocks to 4*4 ie 16. The display of blocks is reduced by commenting out certain code for last column. I am sure all blocks cannot be cleared now(since some blocks in the last column will have pairs in visible blocks). Will need more time to programmatically do the same. The goal being to draw variable number of blocks ie 4*3, 4*4 or 4*5. Here is the source for the modification.