I'll take that occasion to announce a new version, including various new features: Selection areas and operations on those, like Cut, Copy and Paste, as well as flipping and setting priority and increasing/decreasing the tile IDs of the entire area A blank template file of the size specified in the project file is now created if the mapping file does not yet exist Vertical scrolling for large sized maps Tiles on the map that are not in the art file are now displayed as invalid tiles instead of terminating the program Refer to the initial release post (first post in this thread) and the accompanying readme file for more information. Might possibly be somewhat instable, so save frequently as precaution. Download link for the Win32 version: http://geoo.digibase.ca/PlaneEd/PlaneEd_win32.7z Source code: http://info.sonicretro.org/images/4/48/PlaneEd1.1_src.tar.gz Collection of some project files: http://geoo.digibase.ca/PlaneEd/PrjFiles/ If someone has made some additional project files for mappings in the commonly used Sonic disassemblies, especially Sonic 1, I'd be glad to host these as well. "Secret hacking tool" is just an allusion to allegiations from quite some time ago of secret hacking tools being said to be available in the Tech Members' lounge. In fact, I'd appreciate a Wiki article on the tool. GT Koopa: Glad it could be of use to you. I hope you don't mind I included the two project files you provided into the collection. If you do, I'll remove them. Yeah, for getting the art in, you'll have to use some other tool to get an image into Genesis tile format.