In the original StarCraft , game logic was partially hardcoded. Modders could change unit damage or health by editing arrays in a DAT file using tools like Arsenal III, but they could not easily create new mechanics. If a user wanted a unit that cast two spells, they were often limited by the engine's hardcoding.
In the original StarCraft , data was packaged using MoPaQ (MPQ), a proprietary archive format developed by Mike O'Brien. Preparing data for StarCraft involved placing files into these massive compressed archives. The engine relied on a system of file paths and specific directory structures. A unit was not merely a 3D model; it was a collection of disparate files: a .grp sprite file for graphics, a .wav for audio, and entries in a .dat file for stats. Modifying the game required extracting these files, editing them with third-party tools, and then "MPQ stitching"—injecting the modified files back into the archive with a higher loading priority to override the base game assets.
The first step in understanding game data preparation is examining how the engines store and access information.