I always loved the game "Kid Chameleon" on the Sega Genesis growing up. It was always very addicting. Kid Chameleon was a unique game in that you could get helmets that transformed you into different beings. It was also unique in that it was an extremely long game -- over 100 levels! Clearly that was a big deal.
Recently I rediscovered this game, and I began wondering what it would be like to modify the game's levels and create my own levels. Since I'm out of school and have some free time, I decided I wanted to hack Kid Chameleon and see about doing this. After several days, I created a huge collection of notes. I also wrote a program that decompresses and extracts tile layout data from the Kid Chameleon ROM itself. I have some screenshots available:
1 - Displaying basic info grabbed straight from the ROM.
2 - Debugging info showing the decompression statistics being displayed.
Now I just have to write code to compressed the data again and put it back into the ROM. Once this is complete, a level editor can be created.