Most installations on a Windows system leave files behind. This can be temporary files, files that have been created after installation, configuration files or files that have been added by patches. The default file uninstallation routines regularly leave files behind. This can be avoided by using specialized uninstallers (like Revo Uninstaller) that scan a computer system for leftovers and remove them automatically.
These files can be deleted manually as well but this usually puts the effort and time solely on the user. A third possibility would be to run Atomic Cleaner which comes with a mode to clean game leftovers from a computer system.
Atomic Cleaner looks like the usual system cleaners. It can not only clean game leftovers but provides access to a temporary files and Internet cleaner as well. It offers four buttons to start the three different cleanups and one that will initiate a full system cleanup.

