Valves Start.

    
The Valve Corporation was and still is an American video game development and digital distribution.

    This Corporation was founded in 1996 but made famous in November 1998 by its first product, Half-life. Throughout it's early years Sierra On-Line, Inc. was Valves original publisher for games. Although this later on gets replaced. After the success of Half-Life, the team worked on mods, spin-offs, and sequels, including Half-Life 2. These were also a big success.

And that was the kick start for the major Corporation many gamers know of today.