Right-click the game on "Steam", click "properties", and select "internaltest" as the beta you want to opt into. We'll be rolling this out in a more formalized way later.
I have a similar question; I'd like to participate in the experimental branch too. I've gone into properties and selected 'internaltest', but nothing else seems to be downloading. There's a field below for an access key for 'private betas', but I don't know if that's the same thing. Is there anything else I need to do? p.s. I've validated my installation, nothing new came through the Intertubes. p.p.s. Huh, that's interesting. My Steam download history is now showing a completed download: '0 bytes / 0 bytes'. Guess it snuck through while I was posting here. p.p.p.s. The entry on my Steam games list is now "Clockwork Empires [internaltest]. I can't see the difference between the main branch and this one, though.
As I recall, they were optimistically projecting that saves might be added 'this weekend', although I don't know if that was referring to the main branch, or the experiemental branch.
Working on it. Staying up until 3 AM last night trying to get these done is not helping my ability to concentrate today, I will readily admit...
So, we don't need to add a password to opt in to the internaltest version? I chose the internal test version from the drop down list in Steam, but it didn't download anything like I would imagine it needs to do as all other games that I've opted into beta test versions end up downloading the game again.