Client files scraped from McWorld before it was closed.
Source: https://www.reddit.com/r/lostmedia/comments/12bufa2/found_mcworld_is_a_defunct_mcdonalds_mmo_that/
Note that this repository is not even remotely complete; many integral files are missing, and an actual custom server implementation wouldn't get past the Create-A-Member screen.
I have attempted to get in contact with at least one member of the McWorld team to ask for more files, but after a friendly exchange they did not get back to me, and I don't want to pester a grown adult with a career who has greater things to worry about than a McDonald's MMO. Maybe one day a happymeal.com CDN leak will happen, but as it is now not enough people really care about McWorld for any sort of revival to happen. Oh well.