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.

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