I spent the weekend playing around with Rust/WebAssembly too - calling between Rust and WebAssembly is a bit more fiddly than I expected, but I can understand why they did it.
I ended up trying to write a text adventure in Rust/WebAssembly for Ludum Dare (https://ldjam.com/events/ludum-dare/40). Due to other commitments, I ran out of time for the (48-hour) "competition", but am hoping to get something working in time for the (72-hour) "jam", which ends tonight.
(Brief blog on my initial experiences at https://maffydub.wordpress.com/2017/12/02/getting-started-wi... .)