Wouter van Oortmerssen (the guy behind Cube, Cube2 and perhaps more programming languages than all of us together) created a scripting language which is designed for game prototyping.
http://strlen.com/lobster
Note that the language itself isn't that interesting (it's like Python Light with Pascal assignment operator and C++ comments), but the standard libraries itself are made for game prototyping.
Perhaps all the math stuff for 3D is included.
That makes it possible to create a simple Minecraft clone in 66 lines.
http://i.imgur.com/ZZWFkXn.jpg
According to the homepage, it's based around SDL2 and therefore available on all major OSs.
EDIT: The ':=' operator is not assignment, but assignment + declaration. Normal assignment is still '='.