Before Retro-Pixel Castles was on Steam I had a distribution system in place allowing players to play around with the latest bleeding edge development versions of the game called "Unstable Builds". These builds are highly buggy versions of the game, but they are updated frequently and allow users to play with the aspects of the next version of the game as I am developing them. I have brought them back by utilizing Steam's beta program.
Having players play these builds is extremely important to the development cycle, you'll be able to identify bugs early so I can squash them out before they ever get pushed to the next stable build. I encourage everyone to play around with them when they have time and report back with any problems they have.
Setting up your Steam client to use the Unstable Build branch is easy, there is no special access or codes you need to make them available to you. Anyone who owns the game has access to them. Simply follow the steps outlined in this tutorial to get started. Make sure you backup any maps you're working on.
The first unstable build has already been uploaded, InDev 11 Unstable 1, it features a completely new modular AI system for villagers and all the future mobs, from your perspective not much has changed, but it's a pretty big rework under the hood. I encourage you to play around with it and see if your villagers behaviors are working as you'd expect them to. Their behavior will be slightly different, but they should at this point in development be able to do everything they used to do in InDev 10b. Note that in this build children are completely broken.
If you discover any problems with the new AI system, please report them in the Retro-Pixel Castles Support and Bugs subforum.