Some of you might remember when we reported on how NERF is bringing back Lazer Tag to smartphones, the game from the eighties where you can blast each other with invisible lasers. It looks like there is another company, the HEX3, who is creating the AppTag.
It works in the same fashion by putting a smartphone (Android or iPhone) on a gun. The difference is that it uses a high frequency audio signal. All that is required to start the application, clamp the smartphone to the gun, and you are good to shoot. This means that you can put this thing on any gun, provided you have a corded pressure switch.
You should be able to purchase the AppTag from the HEX3 site for $59.99, and should ship in 4-6 weeks.