Your iPhone as a strobe light

Strobe it! is a strobe app. It creates a stroboscopic effect using the iPhone flash or the iPad/Mac screen. 

The strobo (lightning) effect can be triggered with a tap, by dancing wildly (controlled movement of the iPhone) or by using the strobo mode. This signal is sent simultaneously to all connected devices.
This allows the app to create a party room using multiple devices. Any number of devices can be connected via Bluetooth to amplify the lightning effect. The result is a surprisingly entertaining light show – even with just two or three devices!

To match the mood, there is also a kind of psychedelic visualizer, which you can influence through interactions. This is implemented using the Metal framework.