IMHO, you're better off playing something like OpenArena. I understand that the Q3/Q3A brand may have some meaning, but OA provides extremely similar gameplay (the same engine but with new resources) without requiring you to jump through hoops to play it.
I'm using an older (L)Ubuntu, on an old laptop, so I'm not sure how much help I will be.
The Open Arena forums has a suggestion that if there are issues using Open Arena from your distribution's repositories, try using the pre-compiled version of 0.8.8:
http://www.openarena.ws/download.php?list.61 (get the Unified Zip, not the patch).
I would suggest keeping the Open Arena package from the "app store" installed (at least initially, as it should mean that the pre-requisites of libopenal & libvorbis are installed. Your graphics driver in use absolutely must support OpenGL (3D) acceleration. Some basic drivers won't.
After extracting, run openarena.x86_64 (possibly open a terminal, change to the directory where the zip was extracted and type ./openarena.x86_64 then press enter). There is also an i386 version for 32 bit architecture (openarena.i386). Likewise there are 32 and 64 bit versions of oa_ded - these are for if you want to run your own Open Arena server only.
I used to be friends on moddb.com with the creator of this. He was an avid modder, and absolutely LOVED Quake. (made openarena then abandoned it) He was super weird, priorly known as CheapAlert, then completely changed his persona to "leileilol" some kind of 12 year old Chinese girl. Anyways my friend disliked him (back when we were 17) and made a creepy flash cartoon of how he pictured his life (Because this guy seemed to be available 24/7 and seemingly never left the house).
http://megaswf.com/s/2455457 odd cartoon here
Ha, try Open Arena! Yes, the game moves this fast on pretty much every map.
Runs natively on Linux, FOSS.
http://www.openarena.ws/smfnews.php circa 2012.
Had to set up a launcher for the openarena.x86_64 file. Runs from the unzip location, so, portable? Runs on my system :)
You might have more luck posting here: http://www.openarena.ws/board/
What textures do you believe are missing from Open Arena? I believe Open Arena 0.8.8 has all the textures it needs to play Open Arena maps.
If you are playing original Quake 3 maps, or user/fan made Quake 3 maps, you may notice some missing textures.
You can get high resolution Quake 3 textures from here:
https://ioquake3.org/2010/08/24/high-resolution-creative-commons-texture-replacement-pack/
There is also an Open Arena extra map pack addon that can be downloaded here (won't solve your problem - but some good maps):
https://www.moddb.com/games/openarena/addons/openarena-community-mappack-volume-1-v3-re-release
I was thinking for a while that it would be pretty amazing if something like Open Arena got crowd funded to clean it up, and create quality assets. Personally, I find that Quake 3 is still far more entertaining than most modern FPS games. All the new ideas, such as alternate fire, cover, regen, ultimately distract from the action. Quake was pure adrenaline with nothing to distract you from the action, and it's yet to be outdone in my opinion.
OpenArena is open source and multiplayer.
If you don't want people cheating, don't put game logic on the client side- even without source code, people can still figure out how to cheat.
Server side logic won't prevent people from writing bots to play the game, but then nothing really will.
Man, sometimes I miss the old days of arena shooters. Just run 'n gun, no loadouts, no in-game stamina, you can carry a dozen guns, random-ass crap like jetpacks, and who the hell cares you're in a floating prison-castle thing in the middle of a plasma storm? Just turn the other person into giblets!
Aahh well, at least we still have OpenArena, and can still play the original Quakes, Unreals, and Dooms of years gone by without having to go and dig ancient, neglected, and possibly broken hardware out of our closets.
OpenArena. It's a quake 3 arena based shooter that stays very true to the original game. It runs pretty well on junky hardware as well, so it's great to break out in a computer lab.
Warsow and Open Arena are open source shooters in the vein of UT and Q3A respectively. They aren't too intense for an older system to run.