I really wanted to like this and it certainly has the potential to be good, but it has a couple of major flaws. The first is being sent back to the main menu on being caught. Secondly, you don't explain or even hint at what the rules for being caught are. These two issues compound each other to just make the game frustrating rather than challenging.
The first guard type is easy enough to figure out, but the second type requires some trial and error, and that sucks because each time you're sent back to the menu and have to start over from the beginning.