I'm a bit nuts, but I run Wine headless to host a niche product server for software developed on Windows many years ago. Using Wine, I can have one profile/prefix per customer, and run multiple customers on a single box without needing any Windows licenses. The way the original server was developed only expected a single customer per box (since they would be running it on their private network), but many customers have opted to have me host it for them, and a big rewrite was out of the question.
It's been working out nicely for many years, with only a few bumps and bruises in the early stages getting everything stable.
I spent an hour trying to get Ark Survival Evolves server trying to run on wine a while ago. But gave up after a while. I used to host a service providing ark servers :P
I've got some fixes in for wine. But debugging Wine can be quite a challenge, you need a lot of low level understanding.
Agreed, it can be a challenge to debug. I probably spent a couple weeks getting everything working for my app server the first time around. It helps that I control the source code though, so I can lean on some old fashioned text logs to pinpoint problem areas. Wine updates can sometimes break things too (had some problems with early 6.0 releases breaking the network stack), so it's important to hold Wine updates and test new versions thoroughly before updating.
It's an app I coded myself over the better part of 15 years now - it's nothing too exciting, just a LoB app for contract administration with a small but dedicated user base. The version I worked on before the current one was a local-only app. The current version was developed to be client-server. Toyed around with doing a web app all those years ago, but it didn't feel like the web as an app platform was quite there yet. I also had a fair amount of legacy code that was still useful that I didn't want to throw away completely.
Anyway, after focusing so much time and effort on the client-server apps, it is finally time to focus on a web front end (only 10 years or so late!). So I've written a middle-tier (running under Wine) with Nginx in front it. The middle tier translates JSON over HTTP->COM calls, then translates COM->JSON over HTTP on the way back. It's a bit of a Frankenstein's monster, but it works and the approach has meant I can keep a tonne of existing code and keep adding features and improving existing features, which has been nice.
It's been working out nicely for many years, with only a few bumps and bruises in the early stages getting everything stable.