Phantasy Star Disassemblies
Back in the days of the Sega Master System and Sega Mega Drive/Genesis, video games were programmed in assembly, a language very close to the machine instructions that the CPU uses. These were then translated to machine instructions by an assembler. The reverse process is called disassembly, which converts the machine instructions back to assembly. This can be useful for studying how a game works, or to reprogram parts of it.
This page hosts disassemblies of the four classic Phantasy Star games, along with the (Windows) tools necessary to reassemble the games.
A big thanks to lorenzo for his hard work on making and documenting these.