It's an expressive systems language with lambdas. So, anything you would be using C for + the power you get from lambdas and generic types. In a way you could think of it as Go with a more advanced type system, and without the garbage collection.
I'm looking forward to writing a game in Clay to measure its true performance in a realtime system.
Has anybody wrapped a rendering library, do you know?
There was an opengl library at one point, I'm not sure of the state of it now though. I think it still works.
It looks like glut and opengl are included with the standard libraries. Unfortunately I can't find any building information so I can't do anything with it.
Not saying anything bad about the language itself, as I've not used it, but the documentation that is linked does not give me any idea as to why I might want to try it.