Here's my contribution to the Level 23 Enigma. If someone can just figure out where to swap a mirror for a refractor, it would work. It is beyond my primitive caveman mind, however.
"There are several buggy versions of this game floating around. On one version level 23 is impossible. You have a broken one, if on level 23 the initially lit lightbulb on the right is on the right edge. The correct version has this bulb three squares from the edge."