If anyone knows where I can find this list, please link it.
https://support.steampowered.com/kb_article.php?ref=7480-WUSF-3601
What is a CD key and where can I find it?
The CD Key is a serial number with a combination of 13, 18, or 25 letters and numbers - it can be found on a sticker inside your game's case or printed on the game's quick reference card.
The CD Key acts as your proof of purchase for the game - Steam Support may ask for it if you need to establish your ownership of an account. It is recommended that you keep your CD Key in a safe place to ensure the security of your account.
Which retail CD Keys are accepted on Steam?
All retail Valve games and a number of third-party games can be registered to your Steam account. All of the following games can be registered through Steam:
* Valve CD Keys in this format: ####-#####-####
* Valve CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Alpha Prime CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Audiosurf CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Dark Messiah CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Dark Messiah CD Keys may also have been printed incorrectly, please see the Dark Messiah article
* Dawn of War Soulstorm CD Keys in this format: 1AB2-3FGH-456I-K8LM-OP9Q
* Dawn of War II CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Defense Grid CD Keys in this format (Direct2Drive only): 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Empire: Total War CD Keys in this format: 1AB2C-DDEFGH3-IJK4L-MNOPQ-RST56
* F.E.A.R. 2: Project Origin CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Football Manager 2009 CD Keys in this format: 1AB2CD3FGH456I7JK8LMNOP9Q
* GTI Racing CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* GTR Evolution CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Killing Floor CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* The Last Remnant CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Lost Planet: Extreme Conditions CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Lost Planet: Colonies Edition is not accepted on Steam
* MLB Front Office Manager CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* NBA 2K9 CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Prey CD Keys in this format: AAB1BB2C345CDD6E E7
* RACE - the WTCC Game CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* RACE 07 CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Ragdoll Kung Fu CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Railworks CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Red Orchestra CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* SiN Episodes: Emergence CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Saint's Row 2 CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* The Ship CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Silent Hill Homecoming CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Speedball 2 - Tournament in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* STCC - The Game CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Unreal Tournament 3 CD Keys in this format: 1AB2-3FGH-456I-K8LM
* Velvet Assassin CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
* Worldwide Soccer Manager 2009 CD Keys in this format: 1AB2C-D3FGH-456I7-JK8LM-NOP9Q
Opposing Force CD-keys cannot be registered through Steam. Opposing Force was included in a retail Half-Life package. The Half-Life CD-key included in the package will unlock all of the games in that package, including Opposing Force.
Note: Only the retail third-party games listed above can be registered through Steam. No other third-party games can be registered and downloaded using Steam.
Adding Non-Steam Games to Your Games List
Games which cannot be registered through Steam may still be added to your game list for easy access - please see the Adding non-Steam games to My games list topic for more information on this process.