The 'Verify Integrity of Game Files' option is accessible via the Steam client and will ensure the installation is complete. An incomplete installation is likely to produce crashes, a loss of performance or other issues.
- Right-click Vermintide 2 in your Steam library sidebar
- Select 'Properties'
- Select the 'Local Files' tab
- Select the 'Verify the Integrity of Game Files' button
- When complete, close and reopen Steam