That is pretty nice history lesson! I guess the fans wanted Quake Champions far sooner than Id did! According to the Quake Wiki page I just found, it was actually a Quake 2 predecessor that got shut down; or at least the wiki page says Generations Quake 3 is “legal,” unlike its Quake 2 predecessor.
As l look at Reaction Quake 3, it looks to me like they just ported their mod, not any code from Quake 2. Porting their maps was probably an easy process since they had the original map data instead of just the compiled BSPs. And there does not appear to be any kind of single-player campaign. So altogether there doesn’t appear to be too much there that would help me.
What kind of changes did they make to the source code between Quake 2 and Quake 3 that would make it difficult to copy the enemy AI and gameplay logic from Quake 2? Do they use a similar system or did they have to completely redesign things as part of making them work with the new netcode?