Valve Corporation is a famous game development company known for developing popular game franchises like Half-Life, Team Fortress, Portal, and Counter-Strike. They created the Source game engine to power first-person shooters and other genres. Valve also developed Steam, a digital distribution platform for games, and SteamOS, their own operating system for living room PCs and devices. They have become a leader in the gaming market with over 80% of the digital PC game distribution through Steam.