When restoring games from a backup, generally Steam has no problem updating the game if the backup is out of date. Depending on the available hardware, backups may be on DVD disks, NAS or even a file server. See our page on steam game verification.
Upgrading Windows can also make a mess with games. For that reason we strongly advocate wiping the boot disk clean and start fresh.
Generally but not universally, games may reinstall the run-time packages needed.
Completely exit from the Steam client.
- Go to C:Program FilesSteam (or the Steam directory that was specified during installation).
- Locate ClientRegistry.blob and rename this file to ClientRegistry.backup.blob.
- Restart Steam to allow the file to be recreated.
Once that’s done, start Steam again and verify your game cache as shown here:
- Start Steam
- From the Library section, right-click on the game and select Properties from the menu.
- Select the Local files tab and click the ‘VERIFY INTEGRITY OF GAME CACHE…’ button.
- Steam will verify the game’s files – this process may take several minutes.
- Once the process is completed, the Check Window will automatically exit.
- We recommend verifying your cache twice to make sure all files are fully downloaded
Its advisable to make backups of games to reduce the amount of internet bandwidth needed. A secondary hard disk is one idea, burning DVDs or BD disks is another,.