I plan on adding more rooms as well as night time variants, though I haven't decided if I'll charge for those. But these backgrounds will remain pay what you want, and can be used and adapted for any sort of project except AI training or releasing them as your own background pack. Credit me as Spiral Atlas Games.
The backgrounds are slightly edited 3D renders, made in Blender using free assets from Blenderkit and Sketchfab and various toon shaders. I plan on posting a tutorial on how I made the backgrounds at some point, and will try to remember to post it here when I'm done.