- launch steam in console mode - terminal:
/Applications/Steam.app/Contents/MacOS/steam_osx -console
- go to the "console" tab at the top, to the right of shop and library
- Visit https://steamdb.info/ and find the entry for the game you wish to download. You will need to take note of the app ID (should be the first thing available) and the depot ID (navigate to "Depots" in the left-hand-side menu – and select the option from the table associated with content). For demos, explicitly search for the name + demo or go to the "related apps" tab at the bottom, they are normal steam games too, with id and depot
- Back in the Steam console, enter
download_depotwith the app and depot id, then press enter
download_depot <appid> <depotid>
- Steam will tell you the download location like
~/Library/Application Support/Steam/Steam.AppBundle/Steam/Contents/MacOS/steamapps/content/
Depot download failed : missing app info for
-> the app needs to be in your library, even demos
Depot download failed : Invalid default manifest
-> double check that the depot id is correct, not accidentally the branch id for example
credit: https://www.reddit.com/r/macgaming/comments/2idpsc/comment/kk4z69a/