Definition - What does Zerg Rush mean?
Zerg rush is a term used in several real-time strategy games (RTS) to describe an overpowering attack by a player against his opponent, usually early in the game. This term was popularized by "StarCraft". The Zerg, the most well-known playable race in the game, has the ability to rapidly produce small and cheap offensive units called zerglings in a short period of time, allowing the player to overwhelm his opponents forces very early in the game.
Techopedia explains Zerg Rush
With its increasing popularity, Google made a playable easter egg that is activated bye typing "zerg rush" into the search bar. As the search is activated, all letter O's in the word Google start to devour all the search results if they are not clicked right away. When all the results have been devoured, a score board tallies the player's score, which can be posted on Google+.