Zandronum AlternativesFirst-Person Shooters and other similar apps like Zandronum

Xonotic is a free (GPL), fast-paced first-person multiplayer shooter that works on Windows, OS X and Linux. The project is geared towards providing addictive arena shooter gameplay which is all spawned and driven by the community itself.

Quake is a classic first-person shooter game that revolutionized the genre with its fast-paced action and innovative multiplayer modes. Originally released in 1996, it continues to be a beloved title among gamers.

Doom is a science fiction horror-themed first-person shooter video game in which players assume the role of a space marine, popularly known as "Doomguy", who must fight his way through the hordes of invading demons from Hell.

Borderlands is a first-person shooter mixed with role-playing game (experience, specializations) that takes you to a mysterious planet, looking like a futuristic Wild West.

Prodeus is a first-person shooter of old, re-imagined using modern rendering techniques and technology. Experience the quality you’d expect from a modern AAA game, designed with retro aesthetics and gameplay that invoke the tech-imposed limits of older hardware.

OpenArena is a community-produced deathmatch FPS based on GPL idTech3 technology. There are many game types supported including Free For All, Capture The Flag, Domination, Overload, Harvester, and more. There are 17 unique player models to choose from and 12 weapons.

Mafia is a series of action-adventure video games developed by 2K Czech (formerly Illusion Softworks) with the third installment by Hangar 13, and published by 2K Games.

AssaultCube is a free, multiplayer, first-person shooter game, based on the CUBE engine.

Taking place in realistic environments, with fast, arcade gameplay, it's addictive and fun!

Shadow Warrior is a series of first-person shooter video games that focuses on the exploits of Lo Wang, a modern ninja warrior who fights through hordes of demons.

The Mana World (TMW) is a serious effort to create an innovative free and open source MMORPG. TMW uses 2D graphics and aims to create a large and diverse interactive world. It is licensed under the GPL, making sure this game can't ever run away from you.

Alien Swarm is a free top-down shoot-em-up video game by Valve Corporation. It is a remake of the Alien Swarm mod for Unreal Tournament 2004, and it was developed by the original team, which was hired by Valve during the course of the development process.

Freedoom is a WIP a complete free content game based on the Doom engine. It's not an engine, but it's replacement game data with entirely original content, Compatible with a majority of game mods made for Doom. Comes in Three Flavors~.