For security, your device may be set to block installation of applications not obtained from Google Play.
To get installation working, go back to the Home or Applications screen on your device and tap Settings > Security (or Applications on older devices). Make sure the Unknown Sources option is checked on.
You may be alerted with a warning message when changing this setting. If so, just tap OK.
Different mobile carriers and device manufacturers will have different policies on whether this setting comes enabled. Enabling this setting allows your device to accept apps that come from somewhere other than Google Play. Your device needs to accept apps from WildTangent for you to be able to install the WildTangent Games App and play new games.
Go to www.wildtangent.com/GamesApp to download the WildTangent Games App for your PC.