The quite promising ET:Xreal engine enhancement project is one possible exception, even though they just had to sadly announce that they wouldn't make their Nov. 5th first release date (I was originally waiting for news about this until then...).
|ET:Xreal with some Free high quality textures|
As you might have guessed, this project takes the advanced id-Tech3 (Quake3) renderer from the now defunct Xreal project and brings it over to the Enemy-Territory engine (also id-Tech3 based). But besides that it also aims to give the engine a general overhaul and possibly add additional advanced features like real physics etc.
Additionally work has also started to replace the free-as-in-beer media from the original game, with much higher quality CC-by-SA textures to make use of the advanced engine features.
To qoute one of the developers (Eonfge) regarding their plans to go fully FOSS:
"The project we are working on consists of multiple parts. First we have a renderer, which is now fairly stable and pretty looking. Then we have the assets, new high quality assets that make the environment come alive. Then we have the official part from Splash Damage. It's our goal to go independent one day, but until we have all the assets replaced, we will remain a mod. After we replaced them all, we'll be an independent open source game."Lets see how that turns out... alternatively the developer of the awesome looking (but totally non-FOSS) ET mod True Combat: CQB also did express interest in porting his game to ET:Xreal some months back.
On the other side of things it looks like the ET:Xreal fork OpenWolf is turning more and more into a wild mix of different id-Tech3 engines.
Its developer recently announced full compatibility with the id-Tech3 based game Tremulous, and is making his roads towards a quite fully featured general id-Tech3 compatible engine based on ET.
I suspect this is also somehow related to the very similar engine enhancements promised for the quite awesome looking Tremulous fork TremZ:
|New alien model in TremZ|
But rumors are running wild (in face of the log awaited but more or less vapourware Tremulous 1.2), so I can't confirm if the proposed release date before the end of the year is true or not ;)