Several classic Apple II games have recently been subjected to thorough disassemblies.
Last month, Andy McFadden of CiderPress produced a disassembly of Mark Allen’s 1981 game, Sabotage, weighing in at over 5,000 lines of assembly code. It’s the latest entry to McFadden’s website, SourceGen Disassembly Projects, a collection of 6502 disassemblies. McFadden recommends using the Windows tool 6502bench to peruse his disassemblies.
McFadden’s release was preceded by Quinn Dunki focusing her attention on Choplifter, the 1982 helicopter game by Dan Gorlin. Using such tools as Virtual II, HexFiend, and da65, Dunki recreated the Choplifter source code, which she thoroughly commented. She also added her own custom ProDOS loader, making the game more accessible in modern environments. While the source code can be found in GitHub, it’s worth reading her blog post on the subject:
After Dunki completed her work, she came across Robert Baruch’s 2022 disassembly of Doug E. Smith’s Lode Runner. It’s one of many other disassemblies listed on McFadden’s website.
As for the reason to disassemble games, Dunki writes: “Looking at the structure and techniques in an existing successful game is one of the best ways to learn to write your own games.”