Cocos simplifies game creation and distribution with Cocos Creator
Open source library for creative expression on the web, desktop, etc.
The ioquake3 community effort to continue supporting/developing id's
JavaScript-based game engine designed to empower developers
Cross-platform game engine in Rust
Web powered cross-platform 3D, WebXR game engine
Turbulenz is a modular 3D and 2D game framework
Java Client + JS/Canvas Server-Side System, with maintained Objects