What are some alternatives?
When comparing Wrack: Exoverse and Doom, you can also consider the following products
GZDoom - ZDoom is a family of enhanced ports of the Doom engine for running on modern operating systems.
Quake - Quake is a series of first-person shooter video games released by id Software.
DotA 2 - Dota 2 is a Free-to-play, Action-Adventure, Multiplayer Online Battle Arena, Single and Multiplayer video game created and published by Valve Corporation.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Overwatch - Stylized team-based FPS
BioShock - Get the latest information on BioShock, BioShock 2, and BioShock Infinite