The Walking Dead - the 3D action-adventure game from Telltale games - has sold one million copies, the company revealed in a press release. The Walking Dead is an episodic series, with new episodes releasing each month and teased at the end of each episode.

Over "one million episodes" have been sold across Xbox Live Arcade, the PlayStation network, PC and Mac. The sales make The Walking Dead Telltale's fastest selling game yet, despite being the first of five episodes. The title was the top-selling Xbox Live Arcade title for two weeks - probably before the launch of Minecraft: Xbox 360 Edition - and topped sales on Steam and PSN during launch week. The iOS version is launching this summer, the company said.

"Premiering The Walking Dead game series to record numbers across so many diverse platforms is a tremendous achievement that shows the value of bringing strong storytelling and game play together," Telltale CEO Dan Connors said.

The video game isn't a direct copy of the TV series, though does reference locations and characters while pulling characters from the comic book series who don't feature in the TV adaption.

IGN, PC Gamer and the Official Xbox Magazine all gave the game an 'Editor's Choice' award. "[M]oments have more sadness and subtlety in them than most games can muster in 40 hours," The New York Times said.

In the first episode players control Lee Everett, who wakes up after being knocked unconscious. Set to be arrested, he climbs free from a police car and fights to survive.

The game allows players to make choice: an instance in the games ask players if they want to leave a certain area at night, or leave immediately during the day.

The Walking Dead is available now for 400 Microsoft Points on Xbox Live Arcade, or $4.99 on PSN. A season pass is available for PC and Mac versions, costing $24.99. The second episode - "Starved for Help" - arrives this June on the Xbox 360, PS3, PC and Mac.