Pretty hard! (might have been easier with saving, but I played on web). I roughly figured out how to make the bats move around, but getting reset to the beginning when I messed up was too rough. I like the idea, though, and the experience of figuring out how the bats were working was very good.

Played on web ; I like the color scheme, however the controls were clumsy (press right, press down, release right while keeping down pressed: player stops).
The message boxes were pretty annoying too, in-game text would have been more appropriate.
I liked the way you made the bats respond to the player movement, this was a cool idea!

Nice game! I kept trying to figure out the code. I think each generator gives you a letter, which is a hint about which word to select when you move to the left at the entrance. I liked all of the different critters in the level. Sometimes my character was a little hard to see, so maybe make his clothes a little brighter.