Gondoltam, ha már én dobtam fel a gondot, íme a hivatalos lehetőség, ami után nem kell a játékokat újrahúzni:
Refresh Your Steam Files

I believe that Steam's files may be modified, corrupted, missing, or misconfigured. How can I restore Steam to its original state without having to reinstall my games?
Why you may need to refresh your Steam files

Refreshing your Steam files can resolve many issues that can be encountered in the Steam application, store, or games. Performing this operation will ensure that there are no issues that could be resolved with a new installation of Steam, and is a good place to start any troubleshooting process.


Note:

This process will not affect your currently installed games.


Windows XP/Vista/7/8

Completely exit the Steam client.
Open the run dialogue by pressing windows key + r (you can also navigate here from the start menu by typing run).
Type steam://flushconfig then press enter. (If asked to allow this website to open a program, please click Allow or OK).
Restart your computer.
Now, launch Steam directly from the installation folder, not from a pre-existing shortcut (~C:\program files (x86)\Steam).
The Steam application will either appear as Steam or Steam.exe depending on whether your settings show file extensions.


Mac OSX

Completely exit the Steam client.
Open Safari and type steam://flushconfig then press enter
Restart your computer.
Launch Steam and re-test the issue.


Linux

Open Terminal
Type steam --reset
You will see the following: Installing bootstrap /home/[username]/.steam/steam/bootstrap.tar.xz
Reset complete!
Restart your computer.
This should remove and download new Steam files for your Steam client.
Launch Steam and re-test the issue.

Forrás

Én úgy tudom, ha megy a steam akkor azzal minden törlődik a gépről, de lehet nem jól tudom.