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instructions for install!,
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This review is from: Scribblenauts Unmasked [Online Game Code] (Software Download)
To use your product key for "Scribblenauts Unmasked" through the Steam client, visit Your Games & Software Library (www.amazon.com/yourgamesandsoftware) and locate your product key.
After you have your product key:
1. Launch Steam and log into your Steam account.
2. Click "Add A Game" on the lower left side of the Steam screen.
3. Choose "Activate a Product on Steam..."
4. Follow the on-screen instructions to register the game to your Steam library.