We've released the first "prototype" build for Milestone 4 on our Experimental branch (instructions on how to access it here). Please be aware this build is rather rough and exists mostly to help us track down bugs while we finish working on the new content we're adding for this Milestone. To make this easier, we've added a new bug reporter tool which you can access by pressing F11 - this automatically creates a zip file containing the game logs and recent saves so you can easily attach it