If you've used Steam a lot you've probably noticed a few games where Steam tries to install something every time an application is started. This application is intended to tell Steam it is installed so it can quit trying. Spoiler: How to use: 1) Select the VDF for the application you're trying to install. Not all applications have prerequisites so not all applications have a VDF file to select. The VDF usually resides in the application's install directory as either install_APPID.vdf or installscript.vdf. Either should work but I would recommend using installscript.vdf when both are available. 2) Input the application ID number for the product. It should show up in the drop down list acquired from Steam but it might not. The easiest way to get it is to find the Steam store page for the program. For example, here is the full URL to the Dishonored store page and I have bolded the application ID number in it. Input that into the "app ID" field of the program: http://store.steampowered.com/agecheck/app/205100/ Without agecheck: http://store.steampowered.com/app/205100/ 3) Click refresh to try to parse the installscript and search the application ID registry. If it was successful, it will show a list of prerequisite applications in the list box below. 4) Check all the unchecked boxes and start the application. Steam should no longer prompt to install anything. Note: If the prerequisite is, in fact, not installed, right-click on it and select Install to start the installer. Spoiler: Applications known to be helpful on: Title AppID Prerequisite (process if not obvious) 1 Assassin's Creed III 208480 VCRedist, UplayLauncher, kb971512x86, kb971512x64 2 Command & Conquer 4: Tiberium Twilight 47700 .NET 3.5 SP1 3 Darksiders II 50650 DirectX 4 Dishonored 205100 PhysXRedist (msiexec) 5 Hard Reset 98400 DirectX 6 Mafia II 50130 PhysX2 7 Wasteland Angel 46520 MS VC++ 2010 Redist If you know of an application that should be added to the list, post it or private message me. Please provide the title, app ID, and information about the bugged prerequisite in the message.