Everything comes from the original module's resource fork. The art is the original sprites, decoded and recoloured with the module's own palettes. The music is its MIDI songs played back through After Dark's instrument samples.
The rats' behavior comes from the module's 68k code, disassembled with resource_dasm and labelled by hand. Each rat is a state machine: 7-pixel steps, and every six steps a RandInt(1000) roll against its Training odds to nap, sniff or turn round. Every number cites its assembly address.
One deliberate fix: the staggered gates handed the outside lane 43% of Professional wins. The corners now even that out. Gotta have fair rat races.
Now we can all scream at our monitors urging Flamin' Furball to turn around and start waddling again like it's 1994.