WorldForge has been discontinued. Similar apps include Godot Engine, which is free and open source. Other options are Unity, Unreal Engine, microStudio and Defold Engine. There's no shortage of Game Development Tools like WorldForge, with more than 25 alternatives for Windows, Linux, Mac, the web and Android.
Valkyrie is a no-code creative platform that lets designers combine digital assets and create applications and interactive prototypes: where the power of Unity meets the usability of Photoshop.
United Kingdom
Verus Engine is a modern, platform-agnostic 3D game engine. It is developed using C++ and HLSL. It is based on Direct3D 12 and Vulkan graphics APIs. The code is user friendly and well optimized.
Estonia
EU
Reality Factory 2 is a next-generation game authoring suite. It combines a flexible, fully scripted game development environment powered by Python with the Ogre3D engine, and supports all major desktop operating systems.
Orx is an open source, portable, lightweight, plugin-based, data-driven and extremely easy to use 2D-oriented game engine. Orx is mostly written in C, but allows you to develop with it with any language that can interface to C.
Japan
The only true complete development platform for online games. HeroEngine seamlessly integrates the entire client and server architecture required to operate an online game directly into the development process.
United Kingdom
Project Spark is a powerful, yet simple way to build and play your own worlds, stories and games.
United States
Game Builder is an experimental game-building sandbox. Create games within a 3D game world you create. Choose from thousands of ready-made 3D models through Poly. Design game logic by arranging various blocks in a sleek drag-and-drop interface.
United States
UrhoSharp is a lightweight Game Engine suitable for using with C# and F# to create games and 3D applications. The game engine is available as a portable class library, allowing your game code to be written once and shared across all platforms.
United States
Limon is a multi platform 3D game engine mainly focusing on first person games. Focus of its development is ease of use and ease of study. It has builtin editor for maps, animations and GUIs.
AresEd is a high-level and fully featured 3D game creation suite. It is Free and Open Source. When it is finished you will be able to make full 3D games without writing any code (although a fallback to the python scripting language will be provided).
NetherlandsEU
Monkey is a modular language. You can create your own custom modules and use other people's - including the awesome box2d and minib3d modules!.
