Xonotic is a free and open source arena shooter based on the QuakeWorld engine. It features the weapon complexities of Unreal with the movement of Quake (closer to CPMA).
Being FOSS, it is the most "ethical" Arena Shooter and is also available on effectively all platforms. Like Quake, it has a small and dedicated playerbase. 9/10.
Fast paced CTF hook jumping.
Instagib CTF hook.
Movement is the mainstay of Xonotic. Do learn how to rocket jump, strafejump, circlestrafe, and other movement tricks.
Xonotic is able to run on most platforms, though it requires Intel HD 3000/equivalent to run well.