Castle Game Engine - An open-source 3D/2D game engine for ObjectPascal.
Flowlab - Flowlab is an online game creator. Make your own games to share with friends.
Open 3D Engine - Open 3D Engine is an open-source 3D game development engine in real-time.
Wick Editor - The Internet's free and open-source creation toolkit.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Unity - The multiplatform game creation tools for everyone.