PhysX is a proprietary realtime physics engine middleware SDK. It was developed by Ageia with the purchase of ETH Zurich spin-off NovodeX in 2004. Ageia was acquired by Nvidia in February 2008 The term PhysX can also refer to the PPU expansion card designed by Ageia to accelerate PhysX-enabled video games. Middleware physics engines allow game developers to avoid writing their own code to handle the complex physics interactions possible in modern games. PhysX is one of the handful of physics engines used in all of today's games.