A while ago Amazon gave Crytek an awful lot of money and at the time we were not sure what for. It turns out they bought CryEngine and have tweaked it in to their own game engine, Lumberyard, which is totally free to use. The only obligation is that developers must use Amazon’s Web Services if they require third-party servers.
So far not that interesting, but there is a gem of a clause hidden away in the small print which states that you cannot use the engine to inflict harm on anyone – unless this very specific condition is met:
This restriction will not apply in the event of the occurrence of 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.
This makes Lumberyard the first game engine ever to include a clause that references the zombie apocalypse.