An attribute for each thing by its number, all bright on black: 1-4 the objects, red, magenta, green and cyan; 5-8 the antibodies, magenta, green, cyan and yellow. DRAW_VILLAINS colours the picture of the villain in record n with the byte for thing 4 - n, the object that kills it, so the two share a colour. The first byte, for thing 0, is never read. sna2ctl took the first byte for spare space and the rest for text.