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.
9 gesture recognition
Built-in proximity detection
Various main boards support : Arduino UNO/Seeeduino/Arduino Mega2560
1*PCBA-Grove - Gesture;
1*26AWG Grove Cable;
Detecting range: 5 – 15cm
Ambient light immunity: < 100k Lux
Gesture speed mode: Normal and Gaming
Please visit the wiki page for more info about this product.