If you were unable to launch the PC demo for The Darkness II, this may be due to a compatibility issue related to the Nvidia PhysX installer. We have released a patch to address this issue on Steam, so make sure you are running the latest version of the demo.
There is also a workaround for this issue that involves uninstalling your existing PhysX driver:
- Go to the Start > Control Panel > Programs and Features (or Add/Remove Programs) > NVIDIA PhysX
- Select "Uninstall" and follow the instructions in the Wizard.
Once the driver is uninstalled, relaunch the game demo. This will allow the game to install a compatible version of the PhysX driver, and the demo should run without further problems.