Front-end JS for the oil-and-gas industry. Custom, industry-specific customer-facing web applications. Interesting work, but the business logic required by some companies is freakin' terrifying :)
Front-end JS? Need, mainly. Most of the UI/UX people I worked with have not maintained their skills, and I was getting tired of knowing more and doing better work than them in their own field. As it happens, there's a much better market for that work than for the back-end and architectural work I've been doing the past couple of decades.
Oil-and-gas? Luck - I live in a city with a lot of head offices. Eventually almost everyone works for one of them :) It was just my turn. But it looks like a long-term gig, which is great.
Friend of a friend situation - a guy I worked with at another company had a friend who we game with once in a while (board games and miniatures games), and she works for this company. She let me know they had an opportunity and I made the cut :)
They're service applications for O&G companies to help with government regulation compliance, ISO auditing, and well performance, among other things. There are a lot of automated and manual processes that have to be dealt with by the various applications (including some old-fashioned straight-up data entry from graphs made by on-site equipment that get couriered to the office into spreadsheets that get imported).
Some of these are pretty large companies, and they want their tools (even 3rd-party ones) to work certain ways, so some of the workflow logic in the various applications we provide gets pretty hairy. It's impossible to avoid customizing things for some of these clients without losing them.
I was brought on to do a code-review of the newest (unreleased) version of their flagship product. The overseas developers didn't read the spec and management didn't bother enforcing it (hell, they barely bothered to plan it). 2 years of development wasted and it literally doesn't meet a single business need yet. My job then became to lead the rebuild of the front-end and work with the back-end team to make everything awesome again. I get to do proper planning, some nice enterprise architecture and deployment planning, some really cool front-end coding (Angular), and bring some modern (and even current) development practices and tools into a traditionally stodgy corporate development environment :) All with the full blessing and support of the technical lead :D