The words Sierra's website has describes Half Life pretty well...

"Half-Life combines great storytelling in the tradition of Stephen King with intense action and advanced technology to create a frighteningly realistic world where players need to think smart to survive. Since its release in November 1998, Half-Life has won more than 50 Game of the Year awards from publications around the world, including Computer Gaming World, PC Gamer, and CNET's Gamecenter. Half-Life was named ‘Best PC Game Ever’ in the November 1999 issue of PC Gamer, and also won seven 1999 Spotlight awards, including 'Best PC Game' and 'Best of Show', from the professional game development community. These are the only awards given to game developers by their peers."

It was a long two or so years that led up to Half Life's release. The game went through fundamental redesign when we were close to a shippable product which resulted in alot of hard work being disgarded in favour of a more cohesive approach to design. That said, it was a huge amount of fun, and working insane hours was made possible by a hunger for success, a passion for playing what we were building and, most of all, sharing an office with two other guys who were equally (and probably more so) immature as I.