Amazon added an interesting clause to its otherwise dull boilerplate terms of service that include strict rules about how developers can use its new game-development software Lumberyard. Everything goes out the window in the event of a zombie apocalypse.

The quirky message is buried near the end of the 26,000-word explanation of restrictions for using Lumberyard, Amazon's free open-source software for making video games. The software isn't intended for use with "life-critical or safety-critical systems." So it shouldn't be integrated with things such as medical equipment and driverless cars — unless, that is, the US Centers for Disease Control declares a zombie apocalypse.

Here's how Amazon describes it in its terms of service: "A widespread viral infection transmitted via bites or contact with bodily fluids that causes human corpses to reanimate and seek to consume living human flesh, blood, brain or nerve tissue and is likely to result in the fall of organized civilization."

Lumberyard likely won't ever confront zombies, except in virtual reality. But Amazon does hope it will infiltrate user's computer patterns.

Lumberyard is linked to Amazon's cloud service. Developers who build games with Lumberyard and want to host them online must use Amazon's servers or their own. Lumberyard is also integrated with Twitch, Amazon's live-streaming site, notes CNNMoney.

As for zombies, Amazon has some experience with the undead. Its Zombie Protection Store sells brain-protection helmets and zombie costumes.