It powers lichess.org, who have made multiple blogposts about how happy they are with it.
Lichess is a FOSS chess server that somehow manages to compete with chess.com proprietary, distributed, milticloud kubernetes setup from a single VPS. According to them, scala helps.
I would really like to see a setup guide for this. Because if you are throwing a VPS up, they usually just give you a public ip address. I don't really know how you would put a router/firewall in front.