Liminal Finder.

“Liminal Finder” is an instrument of diversion which employeth the sundry sensors hidden within the iPhone to observe the “thinness of the boundary” where thou now standest. This instrument doth neither detect nor prove the existence of other worlds, apparitions, nor any supernatural thing. Location, motion, geomagnetism, air pressure, and the sounds round about thee—their subtlest alterations are gathered and shown as a single observed value. Walk forth and seek the boundary; when the appointed conditions are fulfilled, the gate shall open unto a ten-second Detailed Search by means of the camera.