For the tech-savvy: The Steam Client Service registers itself in the Windows Registry. If that registration is corrupted, the game gets a null response.
The "Failed to Initialize Steam" error in Shadow of the Tomb Raider often stems from administrative privilege conflicts, corrupted files, or security software interference. Primary solutions include running both Steam and the game executable as an administrator and verifying file integrity via the Steam library. shadow of the tomb raider failed to initialize steam fixed
You can keep all 200GB of your games while refreshing Steam itself. For the tech-savvy: The Steam Client Service registers