How can I lower the violence and content for Left 4 Dead?
Some countries require low violence to be permanently enabled (ex: Germany). If you live in a country where low violence settings are required, you will be unable to remove the low violence version.
An example of the Properties window:
In this new window, type -lv as shown here:
Click OK, close the Properties window, and then launch Left 4 Dead. The game should run with less bodies, limbs, and other content.