The Australian city of Canberra will pilot an R18+ rating from this week, ahead of a national introduction in 2013.
The rating has been a long time coming, and follows the submission of the R18+ bill to parlianment in February this year.
The bill will see an end to games such as Syndicate, Left 4 Dead 2 and Mortal Kombat being refused classification in the country, while many games currently under Australia's previous highest rating, MA15+, will be reclassified.
"This is part of a national reform that will allow adult gamers to view R18+ material in the same way that can already be done for film and printed material," said Australian Capital Territory attorney-general Simon Corbell.
"But at the same time it will also provide protection to parents and children by giving parents better guidance about what material is and is not appropriate for people under the age of 18."