Wurfel Engine is an open source 2.5D isometric Java game engine used for the game Caveland.
Wurfel Engine is licensed under a BSD3 license which means you can use it for free, even commercially.
Windows, Mac, Linux are fully supported.
Wurfel Engine renders only what is visible and uses algorithms specially designed for isometric block worlds.
It is also only under 3 MB in file size (+7 MB libGDX library).
A powerful and efficient light engine allows to shade the scene vertex based or via normal map shading.
Wurfel Engine already includes many useful features e.g. weapons.
Using chunks the map can be streamed.
Wurfel Engine uses a 3D world to build the world of your dreams.
With the build in WYSIWYG map editor players or level designers can shape an immersive world with immediate feedback.
Download the Wurfel Engine SDK (source, jars, docs etc.):
If you may be further interested in the technology used in Wurfel Engine, you can read my article on Gamasutra.