About 10 years ago, a friend and I looked into the broken symmetry in the castle of the Maze of Galious: the hidden room with the cross does not seem to have a counterpart. We used a disassembler and openmsx-debugger to find out where the room data was stored and built a map from the definitions in the ROM. That way, we were able to find another even more hidden room, which is obviously located in the mirror position of the "cross room". The catch: it's filled with wall and cannot be reached from the game (without cheating).
Recently we felt like continuing this project. While we were originally only interested in the room tiles, we now spent some (or should I say: way too much) time getting the rest of the map details from the ROM. And we've come a long way.
One thing in particular is worth mentioning: all the messages from the gods are of course in there. And there is a message that is not used in the game. Like several others, it also includes a type. 
Here it is (both in Engrish and in Japanese):
Finally: Is anyone interested in a live stream or recorded video where I explain how I made the map? If so, I'd like to do that. Please let me know if that is something that would interest you.
