Awoo! I solved your biggest issue, mid-game joining crashing the lobby! Now, you should be able to run a match right through to the end even if people join in the middle of it.
Fixed:
- Mid-game joiners no longer cause the host to think it has disconnected
- Shots no longer get trapped in corners
- Shots will correctly reflect if shot inside very thin obstacles
- Item descriptions no longer stay on screen forever
In addition, I have uploaded a default Steam controller profile. This means Steam controller users should be able to play Lupinball without any configuration. If you use PS4 controllers as Steam controllers, they should work too.