I'm going to do a little bit of a shameless plug as a way to show off just what Nim is capable of. If you've ever played one of the many IO games, it might seem familiar to you. Basically I have used Nim to create a multiplayer game that can be played in the browser[1].
I'm planning to write up a more detailed post outlining the architecture of this. But suffice it to say, Stardust is written 100% in Nim. Both the servers and the client running in your browser is written in Nim. The client uses Nim's JS backend and the server Nim's C backend. The two share code to ensure the game simulation is the same across both. Communication happens over websockets.
It's been a lot of fun working on this and I cannot imagine another language being as flexible as Nim to make something like this possible. I already have an Android client up and running too, it also is built from the same code and I plan to release it soon.