While space colony sim RimWorld has been available digitally in Australia since 2013, it was recently put in front of the Australian Classification Board due to a potential console release. That would mean physical copies on the shelves, which need to have an age rating on them. In their wisdom, the Board gave RimWorld a rating of "Refused Classification", making it illegal to sell in Australia, due to the way it deals with "matters of sex, drug misuse or addiction, crime, cruelty, violence or revolting or abhorrent phenomena in such a way that they offend against the standards of morality, decency and propriety generally accepted by reasonable adults".
At the time we assumed this probably wouldn't affect the PC version. So did RimWorld's developers, Ludeon Studios, who wrote in a news post, "We did not expect this to affect the Steam version because in previous similar cases, as with Disco Elysium for example, an RC rating on a console version did not affect the availability of the PC version on Steam."
Turns out we were wrong, and RimWorld has vanished from sale on Steam in Australia. While previously purchased copies remain in their owner's libraries, its Steam page is inaccessible in the region. (Though it's still available for sale direct via the RimWorld website.)
"I'm sorry this news was so sudden and for anyone who is frustrated by this", Ludeon Studios writes. "We are working to resolve this situation and make RimWorld available to everyone again as soon as possible, but we don't yet know what that might require or how long it may take."
While some games refused classification in the past have been taken off Steam in Australia, as was the case with Hotline Miami 2, others remain freely available in spite of the rating, such as Postal 2, Phantasmagoria, Mother Russia Bleeds, and Leisure Suit Larry: Magna Cum Laude. Whether any given game that's refused classification will be delisted from digital storefronts in Australia, or simply kept out of physical shops and allowed to remain available online, remains frustratingly opaque.