The only problem was, while you could sometimes pick up the bat and move it around, it was difficult to really control where to go, especially at the edge of the screen. I thought the perfect addition to the game would be an object you could pick up that would let you float above the walls and explore the kingdom. So my first try at a hack, back in 2003 or so, was to add a hot-air balloon to the game. If you found the hot-air-balloon and pick it up, you could float above the walls.
While I was at it, I tweaked a couple of the room layouts and added a room in the white castle (it always bugged me that there was an "exit" in there that didn't lead anywhere.)
Now, this was back before I figured out how to actually assemble, so the changes I made were extremely tedious: instead of just disassembling, adding some code and reassembling it, I was actually using a hex editor to hack in the instructions using machine language (e.g. $4C $7E $F6 to jump to a patched-in subroutine).
So even though I came up with some more ideas after that (like having the dragons breathe fire at you; adding a shield the player could use to defend against the fire, adding a torch to see better in the catacombs), the idea of hacking in all those instructions, byte by byte, was so daunting I just shelved the idea.
I did submit the hot-air balloon hack here a few years ago, but I made a fairly dumb rookie mistake in making the hot-air balloon so darn hard to find that it wasn't obvious to a casual player that it was even in there.
So tonight I'm finally fixing that mistake. Attached is the new-and-improved Adventure hack, with a much easier-to-find hot-air balloon. Enjoy.
(On a related note, a few months ago, I figured out how to compile assembly, and wrote a whole new game to make use of the fire-breathing, shield and torch (flashlight now) ideas. Except they're fire-breathing ducks, instead of fire-breathing dragons. If you like this hack, you might like that game too.)