Source Engine
Valve’s Source engine is widely recognized as the most flexible, comprehensive, and powerful game development environment available.

Source combines leading-edge character animation, advanced AI, real-world physics, shader-based rendering, and a highly extensible development environment to produce some of the most popular computer and console games. These games deliver the most intense, visually-stunning gameplay experiences on modern hardware, while scaling smoothly on older systems, enabling developers to reach a diverse range of gamers.

Source technology powers some of the most critically-acclaimed PC and console games, including:
  • - Half Life 2 + Episodes One and Two
  • - Portal and Portal 2
  • - Team Fortress 2
  • - Counter-Strike: Source and Counter-Strike: Global Offensive
  • - Left 4 Dead and Left 4 Dead 2
  • - DOTA 2
Thanks to Source’s comprehensive, road-tested collection of tools—the same used to create Team Fortress 2, Portal and the Half-Life 2 series— developers time and effort can be spent building creative gameplay and unique content rather than fundamental systems such as rendering technology or network code or collision detection.

At its core, Source is designed with a modular, component-based architecture that enables the seamless integration of new features and technologies. Since its 2004 debut to third-party developers, Source licensees have benefited from the very latest tools for level design, modeling and character animation, online play and communications, console development, and more—all available at no extra cost or additional licensing fees.

Source’s updated animation system brings expressive characters to life with an unlimited palette of facial expressions that allow them to convey a message without having to say a word. These characters possess the industry’s most advanced artificial intelligence, making them extremely capable allies and foes.

Characters populate beautifully rendered and physically simulated worlds that, thanks to Source’s integrated and versatile physics system, immerse players in realistic and responsive environments. This allows developers to break from authoring the pre-scripted events featured in previous generations of games, and opens the door for the creation of completely new styles of play.

Source’s multiplayer platform supports some of the world’s most played online games—including Counter-Strike and Team Fortress 2—and one of the largest online gaming cultures in the world. Robust networking and multiplayer features include support up to 32-player LAN and Internet games, an integrated server browser, and voice and text messaging.

For more detailed information on this check look at the official website.