Richard Marks has made a walkthrough for the game for playing as the bunny.
There is some discussion of the game in the comments of the original blog announcement - in particular, the author offers this hint: "I guess I’ll give one clue for now, you can test to see if an item is an egg by seeing if you can drop it in the sacred egg chamber. (You will lose it forever though)". Additionally, according to the author there's no red key in the game.
There is a partial walkthrough by Patrick in the TIGSource post comments (see comment number 16). Also of interest: Deadeye has translated the latin from the manticore book (see comment 22).
The game has been discussed in the comments of this JayIsGames article. Of particular note: The devil says the following if you translate the cipher : "You know you are in hell when you transcribe a rebus font to find out what it says.".