The community is also a great place to check out. Try this link for help from other users:
The German version of Fallout 3 contains the German language only. There is no way for Steam Support to modify this regional content restriction.
Please review the Third-Party Game Support topic to determine whether your question should be directed to the game developer or to Steam Support. Sending a support request to the wrong party may result in a delay in processing your request.
Retail CD-Keys for this game cannot be registered through Steam. If you wish to create a shortcut to this game under your Library, instructions can be found here:
Adding non-Steam games to My games list
CD Keys are no longer issued for Fallout 3. The game no longer requires Games for Windows Live to play. If you previously had your CD Key registered to a Games for Windows Live account, you do not need to register it again.
If you're encountering issues with launching Fallout 3, make sure everything installed smoothly.
Exit Steam entirely.
Browse to your Fallout 3 installation folder (Usually C:\Program Files\Steam\steamapps\common\Fallout 3\ or C:\Program Files\Steam\steamapps\common\Fallout 3 goty\)
Run the following installers:
For 64 bit versions of Windows:
For 32 bit versions of Windows:
Reboot your computer and test any issues again. If the issue persists, contact Fallout 3 support.
Downloadable content for this game is available through the Games for Windows Live Marketplace. For more information please see this article.
If you own the Game of the Year edition you can verify that the DLC content is being detected by selecting 'Data Files' from the game's launcher. Within this menu, each piece of DLC should have a check next to its name.
Please make sure to run Steam as administrator and complete all processes outlined here.
If you are having trouble running Fallout 3 on Windows 7 please do the following:
1. Navigate to your Fallout 3 folder (C:\Program Files\Steam\steamapps\common\fallout 3)
2. Right click on fallout3.exe
3. Click Properties
4. Click on the Compatibility tab
5. Check the box "Disable desktop composition"
6. Launch Fallout 3 from the .exe or from Steam
If you are experiencing this issue, please exit the game and Steam in order to complete the following:
Navigate to the following default location:
C:\Users\[username]\Documents\my games\Fallout 3
Open the fallout.ini file using notepad or a similar text editing program.
Use control+f to locate and delete the following line:
Scroll to the bottom of the page and add the following two lines:
Save the file keeping the .ini extension and relaunch the game.