What we know
Return to Castle Wolfenstein in the browser, from the community list this site started with. id released the engine source under the GPL. Details are not verified yet.
Links
Deep dive in progress
This page is a short entry. The full write-up (original game, who built the port, how to play, creators and sources) comes next.
We have not confirmed whether it needs your own game files. The engine is open source. Not legal advice. Never run a launcher or download from a page you do not trust.