Thanks a lot for the detailed feedback!
The auto-advance idea is definitely interesting and worth considering. My original idea was to keep the game mostly passive, but add a few active abilities to use strategically during runs rather than making it fully idle.
I also agree that auto-restarting after death could go a bit too far, since coming back to the tree and choosing upgrades is an important part of the loop.
And the separate music/SFX controls and volume balance are both good suggestions. Thanks for taking the time to write all this!