LOVR is amazing and getting better each day. It's just amazing tool to throw up basic 3D playground for data visualization or for playing with visualized math. The interpreter is tiny in size but feature-full (drawing simple shapes & text, powerful low level graphics API, spatalized audio, physics engine!). Code is simple and elegant C. Community is tiny but wonderful and welcoming.
Currently working on developing a game in Minetest (https://www.minetest.net/), it is also scripted in Lua.