Hello there!
This post will provide ways to install/downgrade Astroneer to earlier versions!
This guide may be edited to fix any errors or to add more information that was obscured.
If you own the steam version of Astroneer:
Step 1:
Go to SteamDB
https://steamdb.info/
Step 2:
Search Astroneer on SteamDB:
https://steamdb.info/app/361420/
Step 3:
Go to the Depots page and click on the Depot ID 361422
Step 4:
Go to the Manifests page and you'll see all of the Manifest IDs of the game
Step 5:
Open the steam console by copying this into your internet browser:
steam://open/console
Step 6:
Insert the following into the console:
download_depot <appid> <depotid> <manifestid>
Replace with Astroneer's appid (361420)
Replace with Astroneer's depotid (361422)
Replace with the manifestid of your choice!
Now press enter
Congratulations! Now you just have to wait for your Astroneer install to be downgraded. This may take awhile to install the older build so be patient.
For those who don't have steam:
Unfortunately Steam (from what I see) is the only one that supports downgrading your games.
However that doesn't mean there isn't other ways to get the builds. As of currently, there's early access versions of Astroneer available for download on the Internet Archive!
Hope this guide was helpful! Please tell me if you have anything you want to add or if there's anything on this post that needs fixing/needs clarification.
That's good you had a lot of fun with both versions!