I enjoy a good brain teaser--fun one!

My only suggestion, make the key slightly larger or a bit more prominent. At some point, the players will have solved enough puzzles to have it memorized, then a way to skink it back down...

I recently put together Hybrids as an homage to a formative childhood game of mine, Logical Journey of the Zoombinis (https://en.wikipedia.org/wiki/Logical_Journey_of_the_Zoombin...).

Thanks for checking it out!