How would I go about extending JME, i.e.- building a derivative engine based on JME? Is that encouraged, or is there a plugin system, which would allow me to effectively build and engine with JME as the foundation/core?
Feel free to build upon jMonkeyEngine, the only restriction is that you must follow the the 3-Clause BSD License.
You should state that your engine or game contains code that is copyright jMonkeyEngine. Code you write is of course your code and copyright to you. You should also include the BSD disclaimer. This is legalese for “If you use jMonkeyEngine or things derived from jMonkeyEngine you can’t sue jMokeyEngine even if it is buggy”
You may not imply that jMonkeyEngine endorse or promote your engine/game.