No, the two different colours are coming from the playfield and the
background. In the area where the 12 sprites are meant to be displayed
Thomas changes the playfield to colour 1 and the background to colour
2. Then he sets up a playfield pattern according to where which colour
is supposed to show, and masks out the shapes with the player graphics.
The two players are actually set to black, like the background in
those areas, where the sprites aren't displayed. So, unfortunately
this routine won't be usable, if the individual sprites need to have
more than two states.
