check prices in your region via steamdb.
if there is no price tag then it simply is not available for your region.

Is there anyway we can contact the developers to allow Australians to buy this game?

引用自 Julius_88：

Is there anyway we can contact the developers to allow Australians to buy this game?

Unfortunately, they have long gone bankrupt. Although why the game isn't available in Australia, I have no idea.

Does anybody know where I can buy this game? I tried GOG, Epic and a ton of other game store companies but no luck. If anyone finds a way to buy this game I would really appreciate it.

yeah, not available in Poland either. Afaik they didn't update/accept the regional price when that was introduced and now they're gone, so there's no one to do it. Literally just one-two clicks from what I heard. I still check in regularly hoping for a miracle. Adored the first two games, but never got to play the last one.

Perhaps better pressure Valve to have some sort of emergency policy in such cases...?

key selling sites sometimes seem to still have supplies of the keys left

Try find fisical copy on the market.
Be sure it can run on your actual OS befor ( it should anyway ).