Accessing Previous Versions on Steam

[Father Ted]

I believe this has been discussed several times by others on the steam forums, but I will repeat it here.
After having bought RimWorld on steam I realized that steam does not offer the option to download or rollback to a previous version, nor does it offer the ability to postpone an update while still being able to play (unless you are constantly in offline mode). So it has peen proposed that, if possible, an option to go back to a previous version using the beta menu in steam, as other games have done, would be welcomed.

edit: It appears that this was already being implemented as I was posting this. If this is so I would be grateful to know how far back we will be able to go. Specifically I am looking to obtain alpha 13 so that I may access certain mods that will not be updated further or are likely to take a long time to update.