about 1 month ago - PDX Katten - Direct link
1. Open your Game Library on Steam

2. Right-click on your game

3. Select Properties from the menu

4. In the Properties menu, select 'Local Files' from the left-hand panel

5. On the Local Files page, select 'Verify integrity of game files'

6. Steam will then verify your files. Please note this can take a few minutes!