That apparently is nothing. The full game will require 50GB's of free space to complete the install process and will occupy 20GB's once the install is finished.
Quote:
Installation Notice: Stranglehold requires 50GB of free hard disk space during the installation process but, once installed, the setup files can be removed or stored elsewhere. If installing Stranglehold to a secondary drive, your system's primary drive requires 20GB of free hard disk space during the installation process.
That is totally ridiculous. There is absolutely no reason for that. No games based on the Unreal 3 engine require anything like that amount of space. I can't stand lazy programming.