The DVB's Portable Content Format (PCF) is a data format designed by the DVB project for the description of interactive digital television (iTV) services.
 It is intended to support the business-to-business interchange of interactive content and to enable deployment on multiple target platforms with a minimum amount of re-authoring.
CAL (the Cal Actor Language) is a high-level programming language for writing (dataflow) actors, which are stateful operators that transform input streams of data objects (tokens) into output streams.
 CAL has been compiled to a variety of target platforms, including single-core processors, multicore processors, and programmable hardware.
 It has been used in several application areas, including video and processing, compression and cryptography.
 The MPEG Reconfigurable Video Coding (RVC) working group has adopted CAL as part of their standardization efforts.
ShiVa3D is a 3D game engine with a graphical editor designed to create applications and video games for desktop PCs, the web, game consoles and mobile devices.
 Games made with ShiVa can be exported to over 20 target platforms, with new export targets being added regularly.
YAKINDU Statechart Tools (YAKINDU SCT) is a tool for the specification and development of reactive, event-driven systems with the help of finite-state machines.
 It consists of an easy-to-use tool for the graphical editing of statecharts and provides validation, simulation and code generators for various target platforms.
 YAKINDU Statechart Tools are available as an Open-Source product (Community Edition) and in a commercial variant (Professional Edition).
 Users are coming from both industry and academia.
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.
 The game is about an audio recordist called Juliette Waters, who records the voices of ghosts through Electronic voice phenomenon.
 She finds herself trapped in an old family park, shut down since a landslide in 1971, and she now needs to use her recorder to survive the night.
Linux Target Image Builder (LTIB) is an open-source project based on RPM, Menuconfig and Perl.
 LTIB is similar in concept to Buildroot and other Linux file system builders.
 LTIB can develop and deploy BSPs for various target platforms.
 A user can develop a Linux image for their specific target.
 The project was initially sponsored by Freescale Semiconductor and later moved to Savannah.
Widgetsets support platform-sensitive development with the Lazarus IDE.
 They act as adapter libraries that provide an interface between a platform-inpedentent sourcecode written in Free Pascal and platform-specific system functions.
 Thus they allow for development of platform-native software without requiring to provide specific source code for different target platforms.
Nyrthos is an action RPG, currently in development by BeerDeer Games, a Czech independent game development studio.
 The target platforms are Windows PC, Macintosh, Android and iOS.
Monkey X is a high-level programming language designed for video game development for many different platforms, including desktop and laptop computers, mobile phones, tablets, and video game consoles.
 The language itself is an object-oriented dialect of BASIC, which the compiler translates into native source code for several target platforms.
 The resulting code is then compiled normally.
 Currently the official target platforms include: Windows (Including the Windows 8 store), OS X, Linux, Xbox 360, Android, iOS, among others.
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.

Question: Sylvio's engine has been extended to how many target platforms?
Answer: 27