If you've felt the need to remove games from your Steam library without deleting them, don't worry. You can easily hide Steam games directly from the client!
Steam has the option for games to be hidden from the library, yet still stay there. These games can easily be found directly from the Steam client!
If you want to add custom games to your Steam library, don't worry. Non-Steam games can quickly be added to the library through the Steam client!
If you have a Steam code or key to redeem for games or wallet credit, don't worry. The codes can be easily redeemed through the Steam client and their website!