I posted this here rather than on Reddit because Dungeon Rats, in additional to being on sale, has 'cheaper than US' regional pricing for Australians on GamersGate and on Gog (but is 'more expensive than USA' on Steam). The Coupon code GameDeals gets you an extra 3% off. Don't forget Topcashback for an additional 5% Cashback (not factored into the above price): https://www.topcashback.com/gamersgate/ You also accumulate a small number of Blue Coins on Gamersgate that you can eventually redeem for free games or DLCs. Don't try using VPNs for even cheaper pricing from Gamersgate; they are very paranoid about it and have lots of roadblocks to prevent you getting games at China/Brazil/Russian pricing.
If you want DRM free, Gog has it for $2.49 USD. I wanted a Steam version this time because it has achievements, and thus was willing to pay a little extra.