Unity - a multiplatform tool for game development, from the very beginning created to facilitate your creativity. Unity provides a comprehensive set of professional quality applications, and ?quite accidentally? contains the most powerful engine this side of a million dollars.

Features
Graphics features:
Shader importing has been massively improved:
? Shaders are imported much faster, especially complex surface shaders. Instead of compiling all shader variants for all possible platforms at import time, now the needed shader variants for needed platforms are compiled on-demand. Shader compilation results are cached under Library folder, so identical compilations happen much faster.
? Error reporting was improved. Errors are reported on correct lines (imagine that!), and errors in .cginc files report the filename.
? Surface shader debugging was improved. No more ?#pragma debug? nonsense; just click ?Show generated code? in the inspector.
? Added Sparse Texture support (also known as ?mega textures? or ?tiled textures?). This is a low-level API feature, see SparseTexture class. Implemented on DirectX 11.2 (via tiled resources) and desktop OpenGL (via ARB_sparse_texture).
? Added stereoscopic rendering on DX 11.1 (requires Windows 8.1 and compatible hardware).
? Introduced support for OpenGL ES 3.0 on iOS devices (starting with A7 devices).
? Graphics: Support for 3D textures in OpenGL ES 3.0.
OS ? Windows XP, Windows Vista, Windows 7, Windows 8