I'm planning to develop an open source Spotify client for Windows in .NET. I'm working on restaurating the old good design and experience of Spotify it was back in 2009, and see this would be appriciated by many who are tired of apps, but also for those who want an true open spotify client to hack on.
However it's a lot of work involved, while .NET makes the GUI interface smoother, the libspotify integration is a bit more compicated. My plan is to create open source client with a Mockspotify (Spotify mockup) so far, and other developer who is intrested can help me to make the integration with LibSpotify.
The restauration of the old sleek Windows client design (CLI tech stuff ) from 2009 and some of it's technology my project I call 'Tesla inteface', and plan to also re-use it for other projects.
If you're intrested, PM me here on the community.
I believe the old good Spotify experience is stuck somewhere in a parallel universe where decisions where different, another 'fork' of this universe (like GitHub branches/forks), and I want to pull it into our universe by re-creating it together.