A mask, as in a shader applied to your tiles via the tiled background would be very inefficient as you would would have to keep the tiles, and have the fx running all the time.
A better way would be to give the tiles their own seamless texture, and vary the look by changing the texture around corners. Something similar to this method:
I have a texture for it, but if I overlap it around the block, and have more than one block (which I do), it would not be seamless:
If you mean generate its look upon loading, then that would really make it load longer, wouldn't it?
Anyways, I've decided to give it a silhouette look instead. The BG is still bricks, but the Walls and Player are black, shadowy figures.
Thanks for helping though.