After seeing this post, I downloaded the free app. I already have a laser cartridge. I hung a USPSA target 10 yards downrange in the basement and zoomed in on it. I had to fiddle with the settings (sensitivity all the way down) and it worked great. Later I gathered up a couple old phones I had laying around and set up a couple more targets. Now I have a small stage set up. I'm just getting started but I can see the possibilities. Down the road it would be nice for the developer to add USPSA or IDPA scoring.
Here is a video of my very impromptu setup of one target. Forgive the accuracy as I couldn't see the sights while holding the phone and focusing on the other phone. (definitely not ready for prime time YouTube) Also, the scoring is a bit off as I didn't have the target calibrated correctly. But you can get the idea.
https://youtu.be/I8nHKyOTBaU