Axmol Engine
Axmol Engine is an open-source, C++ multi-platform engine designed for mobile devices, desktop, and Xbox, well-suited for 2D game development.
  Inky
Inky is an editor for ink, inkle's markup language for writing interactive narrative in games and exports to HTML5
  ORX
A 2D-oriented, data-driven, portable game engine focused primarily on ease of use and powerful features
 
RayLib
A simple and easy-to-use library to enjoy videogames programming
 
Twine
An open-source tool for telling interactive, nonlinear stories
 
Fyrox
A feature-rich, production-ready, general purpose 2D/3D game engine written in Rust with a scene editor
 
CT.js
A 2D game editor that makes its bet on good documentation, visual tools and smooth workflow
 
p5play
JavaScript game engine that uses q5.js/p5.js for graphics and Box2D for physics. p5play was designed by Computer Science teachers to be intuitive for beginners, making it popular at schools and universities around the world.
 
Wonderland Engine
An engine to build highly optimized web-based 3D and XR apps that run on any device
 
Armory3D
An open-source 3D game engine focused on portability, minimal footprint and performance, and integrated in Blender
 
Lisien
A persistent state container and rules engine for the simulation in Paradox or Maxis style games.
  SimulationFramework
A simple and easy-to-use framework for writing small games and prototyping in C#.
 
jMonkeyEngine
A modern developer friendly engine written primarily in Java
 
Castle
Cross-platform (desktop, mobile, console) 3D and 2D game engine
  Cute Framework
Cute Framework (CF) is a framework available for making 2D games in C++. It provides a portable foundational layer for building 2D games in C/C++ without baggage, gnarly dependencies, or cryptic APIs.
  Surge Engine
Open Surge Engine is an open-source 2D retro game engine for creating games using SurgeScript, a scripting language for games.
 
OGRE3D
A scene-oriented, flexible 3D engine written in C++ designed to make it easier and more intuitive for developers to produce games and demos utilising 3D hardware
 
Arcade
An easy-to-learn Python library for creating 2D video games, ideal for people learning to program, or developers that want to code a 2D game without learning a complex framework
  GBDK 2020
GBDK is a cross-platform development kit for sm83, z80 and 6502 based gaming consoles. It includes libraries, toolchain utilities and the SDCC C compiler suite
 
Panda3D
An open-source, completely free-to-use engine for realtime 3D games, visualizations, simulations, experiments
 
Kool
A multi-platform Vulkan / WebGPU / OpenGL game engine that works on Desktop Java, Android and browsers.
 
Pine
Pine is a Java ECS-based game engine that uses the LWJGL library to provide a high-level and developer-friendly framework on top of native libraries.
 
The Mirror
A next-gen game development platform designed to empower developers and artists.
 
Unity
A cross-platform game engine used worldwide. The engine can be used to create three-dimensional (3D) and two-dimensional (2D) games, as well as interactive simulations.
  Mini Micro
Mini Micro is a fantasy console, with a programming language literally designed to be easy to learn.
  Matali Physics
Matali Physics is an advanced, modern, multi-platform, high-performance 3d physics environment intended for games, VR, AR, physics-based simulations and robotics.
 
Ursina Engine
An easy to use, but powerful open source Python powered game engine
 
Torque3d
A powerful, C++ engine, built on literal decades of proven torque technology
  Indigo Engine
Indigo is a game engine written in Scala for functional programmers, allowing game developers to build games using a set of purely functional APIs that are focused on productivity and testing
 
Narrat Engine
Narrat is a beginner-friendly game engine for making narrative games with RPG features, visual novels, interactive fiction, and more