Open-source alternatives to Base

:video_game: Open Source teleportation based first person puzzle-platformer

The ioquake3 community effort to continue supporting/developing id's Quake III Arena

BananaBread is a C++ 3D game engine that runs on the web using JavaScript+WebGL+HTML

Call of Duty: Zombies demake, powered by various Quake sourceports. https://docs.nzp.gay/

Base environment for Red Eclipse and associated source files.

Unvanquished is a free and open source FPS/RTS hybrid game powered by the Daemon game engine. Historically based on Tremulous as a continuation with decades of work over it.

Source code for cross-platform OpenGL gaming engine

Mirror of https://gitlab.com/xonotic/xonotic - Xonotic (superproject containing build scripts and tools to download other repositories and assets)

OpenLara is an open-source game engine and classic game emulator designed to load and execute original game data files from classic action-adventure titles. It functions as a cross-platform game runtime that enables legacy game assets to run on modern hardware and operating systems. The engine features a deterministic physics system using fixed-point coordinate math to ensure consistent movement and behavior across different hardware environments. The project incorporates a component-based entity system and a data-driven level loading process to reconstruct world geometry and object placemen

AssaultCube

Compatible client of Ace of Spades 0.75