What are some alternatives?
When comparing Unvanquished and Battlezone, you can also consider the following products
Quake - Quake is a series of first-person shooter video games released by id Software.
BotBoxer - A first ever robotic punching bag with computer vision
Unreal Tournament - Unreal is a series of first-person shooter video games developed by Epic Games.
Crossout - Crossout is an Entertaining, Action-Adventure, Massively Multiplayer Online (MMO), Vehicular Combat, Exploration and Combat video game developed by Targem Games and published by Gaijin Entertainment.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
PunchLab - Track the strikes you throw at the punching bag