If your gunna copy the tilemap & make that effort why not take the next step & make it playable? If you'd like to uncover the hidden stuff we could venture together. I've just begun experiencing roms as in learning how they work & beginning to tinker with them.

Theres a site called the cutting room floor tcrf.net it's a self hosted mediawiki which is dedicated to discovering all the unused assets, debugs, & prototypes of roms. It's been around a couple of years they I believe partner sometimes with another site called thehiddenpalace hiddenpalace.org which is another mediawiki site but it's more dedicated towards finding prototypes, master source codes, & hacks for specific games.

This kinda invoked me to wanting to discover stuff in video games I played & seeing some in screenshots + videos eagered to try to see what I can access myself & understand some things. Like garbage video files being put in roms for the specific purpose of moving data to the outer layer of a cd. I use a few emulators for specific consoles. I use one that has multiple emulators called retroarch retroarch.com Almost all of them work for me. Then I use pcsx2 for ps2 because retroarch's lprs2 core which is a open source ps2 emulator won't work on my pc for some strange reason unexplained.