Back in 2011, the Mortal Konbat reboot was widely successful here in America, but the game never got the chance to prove itself down under. Australia's Classification Board (which is basically their version of the ESRB) rejected the title, due to excessive and explicit violence. Warner Bros Interactive tried appealing the decision, but was ultimately unsuccessful.
Now, two years later, Warner Bros Interactive is trying again, but this time it might actually work. As Gamespot in the UK reports, last year the Classification Board unveiled a brand new rating, R18+. It's designed specifically for games that have a large degree of violence (and presumably, strong sexual content as well).
Warner Bros Interactive will also be submitting the more recent iteration of the game, Mortal Kombat Komplete Edition, though it was originally released here in America in February of 2012.
Not long ago, Tecmo's Ninja Gaiden 3: Razor's Edge, for the Wii U, was the very first game to recieve the new R18+ rating.