Follow these steps in order. Do not skip the verification steps.

Accumulated temporary data in Steam's cache can disrupt how the client handles digital rights management (DRM) handshakes with older titles. In the top-left corner of Steam, click > Settings . Select the Downloads tab from the left sidebar.

Navigate to the (or Local Files ) tab on the left menu. Click the Verify integrity of game files... button.

He sighed, cracked his knuckles, and whispered the unofficial IT mantra: “Fine. I’ll do it myself.”

: Some players reported that their antivirus software blocked the game from communicating with Steam. Try temporarily deactivating it to see if the game launches.