Microsoft's first video game console was an ambitious effort. With a 733 MHz processor, Nvidia graphics processor and a Windows NT-based operating system, the Xbox was a formidable entry into the sixth generation of video game consoles. In addition to pioneering online subscription services via Xbox Live, the system also benefited from excellent game development from Microsoft Studios.
The crowning achievements of the Xbox game library are Halo and Halo 2, which sit at #1 and 2 on the console's all-time sales and became one of the most critically lauded series in the first-person shooter genre. Microsoft has built upon the success of the Xbox with two successors: the Xbox 360, and the upcoming Xbox One.