Huh, that was quick. Then again, everything I experienced of Jason Rohrer's home invasion MMO-ette The Castle Doctrine last week did come across as essentially finished, so I suppose there's no reason not to release it to the world now. The version the Passage dev has put out is billed as an 'alpha', in that time/Mojang-honoured tradition, and sells for half-price while that's the case.
I believe the Castle Doctrine to be fascinating, and if it's also discomfiting that's because it's the intent. However, lest some level the tiresome accusation that it's an example of a developer being too smart for their own good at it, the other thing to know about the game is that it's also a tight, tense game of base-building strategy, which requires no investment in the socio-political themes in its backdrop.
It's a more modular, flexible take on the trap construction element of Dungeon Keeper, with the added dark thrill of knowing you've perma-killed a rival player if they don't manage to outwit your design. People are going to design some incredibly fiendish, ingenious home defence setups here, and I suspect seeing that'll be worth the price of entry alone.
The alpha costs $8, which includes a lifetime 'subscription' to the main server plus tools to run your own private one, and comes in both PC and Mac flavours.