The development branch of the Godot game engine just received CSG (Constructive Solid Geometry) support. Keep in mind it was just added and you need to build from source, so expect some bugs and glitches for now. CSG can be thought of like super powered boolean modelling, enabling you to prototype game levels extremely quickly by adding and subtracting geometric primitives from each other. You can also now loft polygonal objects to create more complex CSG shapes. Since everything is implemented as nodes, everything can be instanced, animated, etc.
You can check out the new CSG functionality in action in this video, also embedded below.
If you are interested in learning to use the Godot 3 game engine, be sure to check out our complete tutorial series available here.