well, people can't be stuffed downloading a game that's over 10mb unless they know it's really good. COMPRESS IT! Re-Save bmp files as jpg. (use a high quality compressor... not paint. Use photoshop or GIMP and save as full quality, you can barely tell the difference in the graphics, but the file size drops dramatically. (I got a 30MB project down to 10MB using this method.) if its still too big, music files could be WMA/MP3 to be compressed.
Of course, the game itself keeps looking for BMP graphics and doesnt find them, this causes an error. So open up the gdp file in notepad. (right click>open with>notepad) then change (for example)
and do it for every tileset...save it, then run your project.
(you have to do it for sound files as well if you changed them)