Finally got around to adding the functionality to edit the graphics. For now it's just a fixed sized "tile" editor, but it does work so now you can change most aspects of the Pac-man series of games for the 7800. The only other thing I thought would be novel would be changing the number of start lives, but I am not sure I want to go through the effort of identifying where that is done.
You can assign "viewing" colors for the 2 bits (4 colors) for the tile editor. You can assign those colors to either the left or right mouse bottons. Double clicking sets a pixel (2 bits) on the tile editor. Copy and paste works so you can use the clipboard on another tile. I may attempt something more adaptive, but I will settle for funcitional for now. So for now this is what the graphics editor looks like.
As a small change for my previous hack, I changed the dots to hearts. I believe there was a Ms. Pac-Man arcade hack that did this.
and if you want to play it you can download it JRMSPAC_78.3.bin