If you want to download previous versions of A.R.D. you first need to visit SteamDB to find the Manifests for the specific version, this is the only legitimate way you can download old steam games.
https://steamdb.info/depot/1768551/manifests/
Requirements:
Depot Downloader https://github.com/SteamRE/DepotDownloader
Game Version Manifest v0.5.3: 1200339855840944404 v0.6.0: 1710623047994711239
Depot (Constant) Public: 1768551
Steam App ID (Constant) A.R.D : 1768550
Command Line (CMD) / Batch Script
Example: dotnet DepotDownloader.dll -username USERNAME -password PASSWORD -app 1768550 -depot 1768551 -manifest 1200339855840944404
Swap Username with your username, Password with your password, manifest to whatever version you need.
Hey there Exterminators!
Some runs has been identified to have covered certain elements of the game but still followed the main game rules, I made some changes in the main rules due to some runs covering up certain elements of the game that could lead to some questionable verification's, I added