Tremulous Alternatives for Mac OS X

Xonotic is a fast-paced, arena-style first-person shooter with a focus on pure competitive gameplay. It is free, open-source, and offers both single-player and robust multiplayer modes with a variety of weapons and game types.

Cube 2: Sauerbraten is a fast-paced, Quake-inspired open-source first-person shooter with a unique in-game map editor and strong multiplayer focus. It emphasizes quick movement and tactical team-based gameplay.

OpenArena is a free and open-source standalone 3D first-person shooter game. It is a community-developed clone of Quake III Arena, offering fast-paced multiplayer and single-player combat with a variety of weapons and game modes.

Red Eclipse is a fast-paced, free and open-source arena first-person shooter built on the Cube Engine 2. It emphasizes parkour-style movement and mutiplayer action across various game modes, offering a refreshing take on the genre with a sci-fi aesthetic.

Urban Terror is a free-to-play, multiplayer first-person shooter that balances realism with fast-paced action. Built on a modified ioquake3 engine, it offers a competitive experience with diverse maps, weapons, and gameplay modes.

AssaultCube is a free, fast-paced, first-person shooter game built on the Cube engine. It offers both online multiplayer and single-player modes, emphasizing tactical gameplay and high performance on various hardware.

Unvanquished is a fast-paced, open-source, science fiction themed first-person strategy shooter. Players can choose to fight as technologically advanced humans or adaptable alien lifeforms, engaging in intense multiplayer battles where both strategic base building and skilled combat are essential for victory.

Alien Arena is a fast-paced, free-to-play deathmatch style first-person shooter set in a futuristic, science-fiction universe. It emphasizes classic arena combat with a variety of weapons, maps, and game modes, offering both online multiplayer and single-player bot matches for intense action.