CopperCube is available on Steam It was Greenlit.

Can create 3D games as real WebGL apps, running inside websites. Doesn't use a cross compiler, so WebGL apps are small and download quickly.

Includes easy to use 3D editor for quickly clicking together 3D games.

It was also written by the founder of irrlicht, although it is not open source.

CopperCube includes a terrain editor. Terrain can be drawn with height painting tools directly in the editor, textures can be painted quickly with automatic texture blending into the terrain. There are also tools for placing grass and bushes, and for distributing meshes automatically over the terrain.

You can quickly develop an experimental working model of the product (prototype), because the engine gives you access to a lot of prefabs, plugins and settings. And, you can use the visual programming to speed up the process, even if later you have to write code in order to improve the final product.

Supports both DK2 and DK1.