One of the newer engine/game projects I have been following closely is Octaforge. It is basically a fork of Tesseract, which in turn is an graphic improvement project by the makers of the well known Cube2 engine.
The main difference with Octaforge is that aims to become a game SDK and platform for easy creation of mods; And one of its prime new features for this is full scriptability with Lua.
Read about their progress on the latest beta here, which also includes this nice video showcasing the new player model and an test map:
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