What is Unity and what can I do with it?

Unity is a fully integrated development engine that provides rich out-of-the-box functionality to create games and other interactive 3D content. You use Unity to assemble your art and assets into scenes and environments; add lighting, audio, special effects, physics and animation; simultaneously play test and edit your game, and when ready, publish to your chosen platforms, such as Mac, PC and Linux desktop computers, Windows Store the Web, iOS, Android, Windows Phone 8, Blackberry 10, Wii U, PS3 and Xbox 360.

Unity’s complete toolset, intuitive workspace and rapid, productive workflows help users to drastically reduce the time, effort and cost of making interactive content.

De momento he empezado por un juego simple en modo arcade, que ya podéis jugar vía web o en versión escritorio para PC/MAC/LINUX. El siguiente paso es hacer este juego multijugador.