Luanti (formerly Minetest) is an open source voxel game-creation platform with easy modding and game creation

The fastest and simplest library for SQLite3 in Node.js.

GCC Front-End for Rust

3D game engine with lua scripting

Cross-Platform C++ 2D/3D game engine

Lightweight, multi-platform, data-oriented game engine.

Nazara Engine is a cross-platform framework aimed at (but not limited to) real-time applications requiring audio, 2D and 3D real-time rendering, network and more.

A schema-based binary format for efficiently encoding trees of data

Simple particle system made in one hour: https://youtu.be/GK0jHlv3e3w

2D, zombie, action game made from scratch in C++