so instead of stealing Quake, you're just going to fully remake it, exactly the same, except now it's free, and likely has horrible lighting, effects, textures, and models? 

I don't see how something that runs in quake.exe, using the id maps is going to have horrible lighting or effects, unless you think quake.exe and so on have horrible effects, and you think the id maps have horrible lighting.

Textures and models are another issue, but having seen some of his other work, leilei does make a concerted effort to keeping a feel. I trust him in this over... just about anyone else, especially on making it look good for the detail. He has done some weapon models (which actually fit in fairly well with Quake) that are sufficiently detailed, but are significantly lower in poly count than Quakes. 

OQPlus (formerly known as the Open Quartz Decrapification Project)

haha, truth. Open Quartz is truly horrible, but I guess they heard everyone loves fighting evil trees.

On the map front, I don't know if you noticed but we're running a remix-a-original-quake-level competition right not, some of them changing the theme and some of them just improving the quality of the architecture. I'm sure if you ask nicely when they're done a load of guys won't mind GPLing their maps. Also I'm guessing you've played the e1m1rmx and e1m2rmx maps that have already been released, if not, try them! The quality is much higher than in the original maps.

Texture-wise, I don't know about copyright stuff at all, but how different do the GPL textures have to be? Could you, for example, resample a retexturing project down to original texture sizes if that retexturing pack was built 100% from scratch?

If that would be legal, I've got a idbase retexture pack that I'm pretty proud of that I'd be happy for you to use for whatever. I haven't GPLed it, but hey, I could, just need to figure out how!

http://www.quakeexpo.com/booth.php?id=6 

and could you possibly post a screenshot or two from what you've done so far? I'm not at a computer which I can run Quake on right now. Cheers. 

if you need maps, this thread tries to track all the maps that have their source code released under GPL:

http://www.celephais.net/board/view_thread.php?id=60094 

Here's a screenshot of Tyrann's Devourer (lol) map with some very quake-like from-scratch textures. Super Shotgun is untextured.
http://openarena.ws/fsfps/devoured.gif
I also made a bunch of skies to use also, since just blue, and purple skies get old. ;D

Also no, unless its totally from scratch (which the quake retexture project ISN'T) it's not allowed. Also, resampled textures look UGLY. Also your retexture pack isn't legally okay.

metlslime - most of those links are broken and/or not gpl :(, would be nice to check out your maps again though. 

someone needs so pay czg's subscription