An early attempt at producing a hand-held 'electronic' tennis game like Pong, BLIP featured a light-emitting diode which tracked across a dark plastic screen. Players had to decide which of three bars the LED would hit, and press the corresponding button before the 'blip' got there. Otherwise, your opponent scored a point. The game was basically a really slow version of Gnip Gnop, and it made an obnoxious racket. - BoardGameGeek