The bug had something to do with the way Steam handles controllers, there must have been some conflicting files that the Steam devs must have forgotten to delete/modify when they updated the other things.
After looking at the error logs and trudging through some of the older forum posts and whatnot, figured out the fix, but to save you the trouble of doing that too, here it is.
All you need to do is:
- Make sure Steam is completely closed
- If on Linux: Delete the contents of your Steam folder “EXCEPT” the steamapps folder (in case you have it in the default location, if not then DO delete everything there),
- If on Windows: Delete the contents of your Steam folder “EXCEPT” Steam.exe and steamapps folder.
- Restart Steam, let it auto-update and redownload those files
- (If needed, re-add the custom location of your steamapps folder so you get your game library back)
- You’re done! Now Shovel Knight will launch like usual
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