Developer Valve and publisher EA will be forced to release a modified version of multiplayer-focused zombie shooter Left 4 Dead 2 in Australia.

The unedited version of Left 4 Dead 2 was originally refused classification by the Australian classification review board in September due to its depiction of "realistic, frenetic and unrelenting violence", a decision which was appealed by Valve and EA.

At the same time they launched their appeal the pair also submitted a modified version of the game for classification. It was subsequently granted an MA 15+ rating, clearing it for release on November 17.

The appeal to secure a rating for the unedited version of the game has proved unsuccessful, with a three-member panel of the review board unanimously determining that the game didn’t meet domestic classification regulations.

“In the review board’s opinion, Left 4 Dead 2 could not be accommodated within the MA 15+ classification,” it said. “The computer game contains a level of violence which is high in impact, prolonged, repeated frequently and realistic within the context of the game.”