Unity is a multiplatform game development tool, designed from the start to ease creation. A fully integrated professional application, Unity just happens to contain the most powerful engine this side of a million dollars.
A low cost system that allows for the freedom to build almost any game that can be imagined from a 2d to 3d to beyond. Integrated VR technology and excellent audio systems make for an immersive environment. Consistent technology updates and an active community make the system extremely flexible and advance its' usefulness all the time, keeping it from stagnating.