I've not had a chance to go back to Jason Rohrer's fascinatingly bleak, tricksy home invasion MMOette The Castle Doctrine since launch, but it's now on update 8 and has seen a number of changes. Most headline-making (as you can see) of those is the concept of perma-perma-death.
It was always the case that getting your character killed while trying to steal from another player's house (or ineptly navigating your own lethal home defences) meant that character was dead forever and ever, amen, but now, optionally, you can not even have an option of starting a new character on your server. As in, everyone playing on that server knows they can't come back (at least not without buying another account, presumably) if they get it wrong, so in theory the cold war aspect mounts as extreme caution - and extreme defence - is employed.
Perma-perma-death servers exist alongside, rather than instead of, plain old permadeath servers, so no-one's forced to participate in this experiment of ultimate brutality. But you probably should, just to see how it feels. The fear, the terrible fear.
Also added since launch (back in version 6) are blueprints, which allow you to get some sense of a layout of a house before invading it. That's actually quite a huge change, as it essentially means security setups are that based on the The idea is that it stops people from relying on The Lady, Or The Tiger? guessing games for their security setups. In other words, proper puzzles, not enforced gambles, are the order of the day.
The Castle Doctrine sounds as though it's very much a project still in motion - hopefully I'll get the chance to revisit it a few months more down the line and see how much it's evolved.