Hi! I am one of the two developer of Unit3D Pinball. Just came to say that I tested quickly and having the same issue: UP is running in background but no display. Tom: I guess that it is because you start simulators using a AHK script or similar: UP is looking for window handle and can't find it. We had to trick our Unity engine to fake fullscreen and this was the only way to do it. Contact me directly if you'd like us to make some changes. Cheers!