I started one in Go a number of years ago[1] and I feel I managed to prove to myself that a pure email interface is possible and actually really convenient in some cases. I even managed to implement over 20 games[2]. It was only ever used in my closed circle of friends, but we played thousands of games and many found it simple to participate in slow periods at work or school.
If anything, my biggest takeaway was that if you want to really reach a level of expertise in a new technology, you need to find a project that you can pour your heart into. I've probably breached 100k LOC for the project and I've been working on it for over half a decade. I'm currently redoing the project in Rust as an attempt to become highly skilled in that[3].
[1] https://github.com/Miniand/brdg.me