The documents are a bit broader, encompassing other platforms’ Chicken Run games (including an unreleased GBA title).
CodeBound released the source code, development documents, and 52 prototypes for Chicken Run on GBC
Submitted 10 months ago by Rockafeller@preserve.games to gamehistory@preserve.games
https://archive.org/details/chicken-run-gbc-source-code-sep-7-2000