alt Hacker NewsYeah, but Half Life 2's Source engine was itself a continuation of Goldsrc which was itself a continuation of the Quake 1 engine. The lineage is there but beyond a certain point it's not really Quake anymore.
GZDoom/UZDoom is a similar grey area, it is built on the original Doom codebase but they've added so many features that it's practically its own distinct engine now. Those forks can even render arbitrary 3D models, which OG idTech couldn't do until Quake.
We'd have to come up with definition of quake :-) FTE has a lot bolted on it but the focus us in Quake, quake mods, lifting some limitations and making mod dev convenient.
But it is the same overall code structure, the same game, etc.
All these oss quake engines, are they quake? Ironwail, quakespasm vkQuake?