What is "gnop!"

Gnop! is a freeware computer game created by Bungie. It was a simple Pong clone written and released nearly 20 years after the original. The name Gnop is Pong spelled backwards. The game was created by Bungie co-founder Alex Seropian in 1990, almost a year before Bungie's official incorporation, but bore the Bungie name on itself and was referred to as "Bungie's first game" in official Bungie materials. The game proved reasonably popular among Mac gamers because it was free and user-friendly. Seropian also sold the source code for the game for 15 US dollars.

Gnop! was later included in several compilations of early Bungie games, including the Marathon Trilogy Box Set and the Mac Action Sack.