Open source projects
Arkham Development released some projects in open source:
All Arkham PC demos written in Basic and x86 assembler (from 1991 to 1998).
One Arkham Amiga intro and an unfinished Amiga demo written in 68020 assembler.
A complete 3d engine written in x86 assembler.
Arkham demo PC tools (paint program, sound tracker, modeler, picture and 3d converters) written in Basic and x86 assembler.
You can access to the sourceforge project here.