Unity Technologies , the company behind the Unity game development platform, has closed a $5.5 million funding round led by Sequoia Capital. Unity is a powerful tool that allows developers to build 3D worlds for games running on a variety of platforms, including the iPhone, PC, Mac, and Nintendo's Wii. Unity has recently been seeing strong growth on the iPhone, where over 250 games are now using the toolset (the company says that these games see up to a 3x performance boost when they're using Unity versus other solutions). Games built on the platform span a variety of genres, including boxing , driving , and even a Samurai game (all iTunes links). Outside of the iPhone, games that were built using Unity include Cartoon Network's MMO FusionFall, and EA Game's Tiger Woods . TC50 finalist Hangout.net also uses Unity.