Reading through source code for old games is always fascinating. Any developer worth his salt should take the time to explore this area. The tricks that the engine programmers used to squeeze every last ounce out of the hardware are truly inspiring.

I can appreciate how much effort has gone into this project. For years, I've been working on disassembling and commenting the Sonic 2 Master System engine (https://www.sonicretro.org/asm_svn/Sonic%202%20SMS%20Disasse...) and it's still only about 80% complete.