release notes:
The levels are the alphabetic files.  You can play different levels by renaming the alphabetic files.
(the demo plays the levels in order; the game reverses levels 2 and 3)
The models are the numeric files.  I added a character selection option.
Press space during joystick calibration.  Afterwards, the selection list will show.
Type in the number for the model that you want.  There are two characters in every level.
You can use any model multiple times, even within the same level.
(for the last level, if replacing Sloth, the model will "walk on air" to ensure the proper height)
I have assigned the models as follows:

1	Chunk
2	Mikey
3	Mouth
4	Brand
5	Andy
6	Data
7	Stef
8	Sloth

Technical note: the game uses almost the entire range from page 8 onwards, except for a 1kb range beginning at $b800, and page $bf.  It wanted to be ported to ProDOS! :-)

I created this during a conference at Microsoft, because my talk was cancelled (and the play-testing drew a crowd).  I hope that I didn't introduce bugs while I was listening to the other talks.