Sylvio's engine has been extended to how many target platforms?
Sylvio (video game): Sylvio is an indie-developed first-person horror adventure video game released on Steam in June 2015 for Microsoft Windows, PlayStation 4, Xbox One and, OS X, utilizing the Unity engine. Unity (game engine): Unity is a cross-platform game engine developed by Unity Technologies, which is primarily used to develop video games and simulations for computers, consoles and mobile devices. First announced only for OS X, at Apple's Worldwide Developers Conference in 2005, it has since been extended to target 27 platforms.
27