I am looking for something colorful. Like DOOM, but in Quake. I adore DOOM, and I am having a lot of fun with vanilla Quake. Playing makes me miss the colorful environs of DOOM.

Any suggestions?

There are source ports like engoo that let you change the colouring of the entire game, but I suppose that's not quite what you're looking for.

As regards more colourful levels, the excellent mod Arcane Dimensions features many huge maps that are all in line with Quake's general look and atmosphere, but are still very distinct in style and also colouring. One level is a monestary of sorts surrounded by a graveyard, one's a huge fortress clad in snow, another is an underground facility with lots of lava lakes, etc. They are all equally well made, though, and great fun to play.

Here is a screenshot of just the hub area: http://i.imgur.com/eBBn3xY.jpg

That looks so great! I went and downloaded Arcane Dimensions, Quakespasm, DOPA, and the music fixes. I will have to look into how to make mods for Quake. I am sure people have textures I could use, or I could modify textures already in the game. Maybe I can create something that looks slightly less colorful than DOOM 4.

Do you have any other suggestions, mod-wise?

Have fun with it then! Quake mapping is supposed to be entertaining as well, although I know nothing about it.

I don't know any other mods/maps, but there are lots to be found here at quaddicted.com: https://www.quaddicted.com/reviews/

Also, I came across this tumblr site which shows screenshots of many different maps, that should help you find new stuff: http://quakemaps.tumblr.com/
The subtitle is even "They're not brown - they're beautiful!" so it's right on, haha. The most recent posts are all about Quake's original maps, but starting (or rather ending) with page 4 it's all about custom maps.

That is great, thank you so much! I was just thinking that in the vanilla game there is a criminal lack of stained glass in the game.

The original Quake is somewhat handicapped by its 256-color palette. Doom engine games were more colorful, but Quake had to sacrifice some colors to allow for more shades that are required to make the natural light falloff work without excessive banding (and there's still plenty of it). Doomy games don't suffer as much since they use sector based lighting with sharp transitions and hard shadows.

That said, the quake palette could be better optimized, and indeed a good artist should be able to make nice lush cathedrals even with the limited palette.

That makes sense. I wonder what Quake would have looked like if they kept the vector lighting. I would like to see the Doom color pallette in Quake. It seems we have the ability to use a wider array of colors in the contemporary engines.

Checked a bunch of big mods for Quake. The most closest to Doom would be Warp Spasm mod (works best on FitzQuake Mark V). The most colorful game for me is not Doom but Heretic and the most closest to the latter is Soul of Evil (tested on Quakespasm 0.93)

links:
Warp Spasm (by ijed, 10.05.2007) > best spiritual successor to Doom 2 on Quake engine
https://www.quaddicted.com/reviews/warpspasm.html

Soul of Evil (by Dustin "Tronyn" Geeraert, 01.04.2002) > best mod based on Heretic in Quake universe
https://www.quaddicted.com/reviews/soe_full.html

Nehahra (by Nehahra Team, 17.08.2000) > best Quake 1 re-imagination ever made (cutscenes are cheesy, combat is awesome), works best on Mark V (Quakespasm doesn't support it at all)
https://www.quaddicted.com/reviews/nehahra.html

Quoth (ver. 2.2 (fixed) > currently hosted only on Tome of Preach website, for some reason this is the most updated version and it is needed to run most modern mods, for instance latest Func Map Jam #9 pak works only with this version.
https://tomeofpreach.wordpress.com/quoth/

Quoth (ver. 2.2) > needed for Warp Spasm and many other mods
https://www.quaddicted.com/reviews/quoth2pt2full.html

FitzQuake Mark V (source engine)
http://quakeone.com/markv/

QuakeSpasm (source engine)
https://sourceforge.net/projects/quakespasm/files/

Custom Gamer plays mod Quoth E1M2 (Remix of the Damned by Kell)
https://www.youtube.com/watch?v=CyT9CkCB_zw

Custom Gamer plays mod Into the Shadows starting map (Temple of Swords by Sock)
https://www.youtube.com/watch?v=FcoMu-w1dvE

P.S. Play on Hard difficulty (Skill 2) for best experience

Look up JoeQuake.
http://joequake.runecentral.com/news.html

First of all JoeQuake is a sourceport engine, it's not a mod.

Second of all what's so good about that particular engine? Here is a link with FitzQuake Mark V with JoeQuake visual effects enabled. IMO look completely out of place.
https://www.youtube.com/watch?v=h13Wv0I5pV8

I suggest you to check Quaddicted for mods with knave textures, the problem with Quake colorless lies in its 256 color pallete with lots of grey. Here is a link just in case so you can check which colors are available.
https://quakewiki.org/wiki/Quake_palette

Notable mods with knave textures (don't forget about Quoth mod which needed for many good mods):
https://www.quaddicted.com/reviews/contract.html
https://www.quaddicted.com/reviews/red777.html
https://www.quaddicted.com/reviews/arcanum.html
https://www.quaddicted.com/reviews/sksp2b.html

Link to Quake Revitalization Project
http://qrp.quakeone.com/downloads/
> HD textures for Quake and its both Mission Packs, again FitzQuake Mark V supports it (all you need to do is to unpack it from .7z, then unpack it from .pk3, lastly put folders textures into id1, hipnotic and rogue folders respectively)
> IMO looks out of place, it's like playing Quake in DarkPlaces engine all of the sudden, yuck...

Link to 7-zip:
http://www.7-zip.org

P.S. FitzQuake Mark V ver. 1.36 and QuakeSpasm 0.93 are the best sourceport engines for Quake at the moment, they are based on FitzQuake by metlslime, latest ver. 0.85 was released on Feb 12 2009. If you have issues with OpenGL you may also try Mark V DirectX9 and DirectX8 versions which work fantastically well.

First of all, no shit. This is excessive pedantic overzealous hair-splitting that doesn't meet the spirit of the question. Turn down your asperger's.

Second of all, it specifically addresses the question insomuch as it includes colored lighting while maintaining compatibility, which you would know if you did a modicum of research. There's going to be little to address the Quake engine's color short-comings due to its 8-bit palette and lighting. Specific levels perhaps with new textures, but all this is irrelevant. The OP can decide for himself if this is sufficient.

Well, thank you for your informative reply. Just that you know it wasn't my intention to offend you in any way. And i'm sorry about your reaction.
I will definitely check JoeQuake for its colored lighting.
I already tested static colored maps for Quake and its mission packs (works for almost all modern sourceport engines), looks very similar to Quake 2 (all you need to do is to place "maps" folder to corresponding ingame folders "id1", "hipnotic" and "rogue"):
http://quakeone.com/markv/extras/vis_lits_id1_hipnotic_rogue_free_standing_files.zip

https://quakewiki.org/wiki/External_Lit_And_Vis_Files

Here you may find colored light maps and transparent water files for most commercial (all except XMEN, Aftershock and Dark Hour) Quake Mods and notable free mods as well.

P.S. If someone knows where one can find Quake Dark Hour mod full (not demo) version, please let me know.