[sbarre]

Valve did have a few key people (not to mention complete access to the best 3D engine source code at the time) who really did know what they were doing.

Keep in mind that building video game levels, models, animations and such back then was dramatically simpler than it is now.

One person did all the texture work for the whole game. One person did all the sound effects and music, and also coded the DSP engine to add real-time sound manipulation based on the environment.

You can do a lot with a few very talented people who are willing to guide a whole bunch of smart, eager and motivated folks.. which I think is what happened at Valve.