The sensor on Grove - Gesture is PAJ7620U2 that integrates gesture recognition function with general I2C interface into a single chip. It can recognize 9 gestures including move up, move down, move left, move right, etc with a simple swipe of your hand.
Following is a video which using Gesture sensor with matrix to display the direction of hand.
We can utilize the gesture to adjust the sound volume, control a robot. Or we can make a remote-control unit, which is able to operate many devices at the same time via a gesture sensor.
9 gesture recognition
Built-in proximity detection
Various main boards support: Arduino UNO/Seeeduino/Arduino Mega2560