Happy Elixir user here. At work we have a use case that isn't covered by José's high-level overview of the domains Elixir's used in: we run a massive multiplayer game server on it. This is actually a really good fit. (It kind of rhymes with the original use of Erlang, being telecoms infrastructure.) We get outstanding concurrency support, high reliability, and really efficient development times. I can't imagine shipp…
It's not as ambitious as an MMO, but I like to use MUDs to learn new languages. I've been (slowly) working on one to learn Elixir and I'm actually finding the concurrency model somewhat difficult to use for the MUD - especially the single world that every player connects to.
I ended up writing my own kind of software transactional memory library to help me out: https://github.com/stevbov/stm_agent
But altogether my design feels fairly un-Elixir-like. It seems like the language would shine more in a problem space with more process isolation. When it comes to the game world, pretty much any process could potentially depend upon any other process. Especially once you get into scripting NPCs.