This is a great idea! and very well executed, great job!
I like the art, crisp and clear, and the camouflage change of texture is very well acheived.
The guards do not detect "bad cammouflage", right? that could add a lot of depth into the game.
It is a shame it does not have more ranks. In the future, I recommend you to do a WebGL build, that way your game will have more visibility.
Again, good work!