Fully exit Steam. Do not just click the "X" in the corner. Right-click the Steam icon in your system tray (near the clock) and select "Exit" or "Quit Steam."
Sometimes, Windows tries to run the game in a compatibility mode (like Windows 7 or 8) that clashes with the Steam API. shadow of the tomb raider failed to initialize steam fixed
A lack of administrative rights can prevent Steam from properly initializing the necessary services for the game. Running Steam as an administrator grants it the required permissions and is a quick, often effective fix. Fully exit Steam