You bought the Steam Version of Bethesda's Fallout 3 and it just won't start.
You reach the launcher and set everything up. But upon launching the game, the game doesn't start or gives you an "Ordinal error message" and nothing happens.

You look up on the internet and find outdated guides and broken links that lead nowhere.
Hearing multiple complaints and misinformations, I decided to make this guide.

When opening the game initially, you are going to have two issues:

-Eighter nothing happens at all
-After applying settings in the launcher that opens and trying to launch the game, you are met with the Ordinal Error message.
-Open the game's files location in Steam directly by pressing the Cogwheel on the Steam Library page of the game. Click Browse Local Files. Which opens the game files.
-Right click on Fallout 3, open Properties, go to the Compatibility Tab.
-Check Run this Program in compatibility mode for. Click the scroll down and choose Windows XP (Service Pack 3).
Note: Also works with Service Pack 2 if you don't have access to the Service Pack 3 for some Reason.
-Check Run this program as an administrator

So this should take care of compatibilty issues.
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-Next step is to download the Microsoft LIVE Gaming for Windows
(( Previous Link Removed due to security concern ))

-Create a new folder and extract all the files downloaded in it.
-Put the folder into the Fallout 3 game folder
-Create a copy of the Fallout 3 application (not the .exe) for backup and leave it in game files
-Slide the original Fallout 3 application into the folder containing the extracted files for Microsoft LIVE Gaming for Windows.
-Run the Setup File Application
-Continue and you will reach a Login Page. Close it with the X in the corner. No need to Login.

Now try launching the game from Steam again and it should work.
Tested with 6 users and it worked for all of them.

Feel free to share your troubles if you meet any or if anything needs to be clarified.
You can enjoy the Capital Wasteland on Steam.