http://levellord.toxicsheep.com/Index/K ... 20Patches/
Basically this is what the game uses to define what 'character' the sprite is; whether it blocks Keen or not, whether it acts as a foot, Lindsey of Lick. It doesn't however affect whether it kills Keen, which can be a problem.
A highlight of my studies is:
Code: Select all
#Allow impossible bullet trick in Keen 4
%patch $E63C $0F $00