Just realized I've been lurking here for awhile but never said hi or introduced what I was doing with Leap Motion.
I am one of many developers involved in the Open Source game engine Godot: http://www.godotengine.org/
I've been responsible for adding initial support for VR to this engine and this is slowly getting some traction even though there are a few rough edges still to work out.
I also got involved adding Leap Motion support to this engine both for normal desktop games and for VR games. A first version has been working for a few weeks now and while I need to add a few more features it's behaving nicely. At this moment in time it does require building the game engine from source and only Windows is supported (the game engine also runs on Mac, Linux, Android, iOS, UWP) as its based off of Orion. The next release of the engine should come out any day now at which time the Leap Motion support will be downloadable from the free asset library that comes with the game engine.
You can follow the project for this here: https://github.com/BastiaanOlij/gdleapmotion
So in case you're looking for a free game engine to use that has Leap Motion support, try it out, give me some feedback, help me make this loads better