Things You'll Need
Instructions
Open your web browser and go to the Unreal Development Kit website.
Click the "Download UDK" button.
Download and install the latest release of the Unreal Development Kit. Launch the application.
Click the "File" menu and select "Open" from the drop-down list.
Browse to the folder containing the UPK file you wish to open.
Click the UPK file you wish to open and click the "OK" button. The file will be extracted and fully editable with the Unreal Development Kit.