RimWorld is an engrossing simulator about overseeing a space colony—it's kinda like Dwarf Fortress in space. Because of the freedom it provides, and how detailed the simulation is, a lot of really dark things can happen, which is probably why the Australian Classification Board has effectively banned the game.
Stop right there though, because RimWorld has been available to Australian buyers on Steam since the beginning of its Early Access stint in late 2013. The reason for the game's new appearance on the Classification Board website appears to be due to imminent console ports: Double Eleven Limited is the applicant, a studio which has ported the likes of Rust to console.
A console port hasn't been announced for RimWorld, but it's apparently coming, and Australian console gamers won't be able to buy the game unless Ludeon Studios or Double Eleven make some changes. Here's the Classification Board's beef, by the way:
The computer game is classified RC in accordance with the National Classification Code, Computer Games Table, 1. (a) as computer games that "depict, express or otherwise deal 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 to the extent that they should not be classified."
If you're an Australian who already owns RimWorld on PC, the board isn't going to take it away from you. But more importantly, it's unlikely this decision will lead to the game's delisting down under: Disco Elysium was also banned in the lead up to its console release in Australia, but remained available on all PC digital storefronts anyway (that ban was eventually overturned).
Whatever happens, I've reached out to Double Eleven Studios and will update if I hear back. Cheers to Kotaku for the heads up.