If you decided you don't want to give Quake Live a go, which is honestly a better choice for playing online, you can still do some things to run Quake III: Arena more comfortably.

First of all, you need to get Quake III

You can get it on Steam, GOG or any other platform of choice. Both versions come with the Team Arena expansion. All you need is the baseq3 and expansionpack folders from the game's folder.

Download ioquake3

ioquake3 is a modern source-port based on the original source code with improvements and cross-platform capabilities. At the moment, the website is broken after a migration and the downloads don't work, direct links to the builds can be found below:

• Linux
• Windows
• macOS

Update: the download page seems to work now, but I will leave these just in case.

Inside the archive, you will find another archive, contents of which you have to put inside your Quake III installation folder.

Creating a config

Easiest way to configure the game is creating an autoexec.cfg file inside baseq3 folder. Copy the following contents into the file:

r_mode -2 // automatically selects your native resolution
com_maxfps 125 // explanation: https://www.youtube.com/watch?v=P13KmJBNn1c
com_hunkmegs 128 // even Team Arena crashes if you don't increase this
r_fullscreen 1

Recommended mods

High Quality Quake - for HQ icons and fonts.
Flexible HUD - widescreen HUD support.

Finishing up

Now you can run the ioquake executable and enjoy the game!