It's a particularly strange decision, considering the fact that the original Wii version was released as MA15+ without incident, but the Classification Board's issue is with a new 'Hardcore mode' which has been added to the game.
"The "Hardcore" game mode allows players to play in a manner that exceeds strong in impact," claims the report, "engaging a headshot-only mode which results in frequent, detailed blood and gore as the zombies and mutants [sic]heads explode into bloody pieces that spread around the environment and onto the screen. The game also contains an "Extra mutants mode" which increases the amount of mutants the player must kill to proceed, resulting in an increased intensity and frequency of violence. In addition the game contains a baby mutant that jumps onto the screen and explodes into bloody chunks when killed."
SEGA Australia has already announced that it will be resubmitting the game for classification in the near future.
"There are far worse titles currently available in the marketplace which involve more than shooting down mutants in humorous circumstances," claimed Managing Director Darren Macbeth We will do everything we can to prove that House of the Dead: Overkill is worthy of an MA15+ rating in Australia."