A fast, self-contained, highly customizable Aseprite-to-Unity importer
3D C++ Game Engine - yet another open source game engine
Modern 3D engine and IDE written using C# and C++.
A 3D Snake and 2D snake
Data-oriented and data-driven game engine written in Rust
Mad Vandal's FortressCraft Mod Source Code
A 2D game engine and level editor
Clojure in Unity
A complete framework for Godot to create beautiful and complex AI
A cross-platform 2D game engine
Planimeter Game Engine 2D - LÖVE-based game engine for Lua
Example code for creating a 2D platform game in Java.
Test project with a 2D platform game developing in Godot 3.1
a 2D Game Development Framework
Web powered cross-platform 3D, WebXR game engine
A picture worth a 1000 words
Flex roguelike
A first person multiplayer shooter example project in Unity
scriptable game engine with built-in support for 2D graphics and sound
The Atomic Game Engine is a multi-platform 2D and 3D engine
A little game I strung together using Unity 5
A snarky 2D management game about building and running a dungeon.
2D ARPG Engine