Sjmarf
themoonisacheeseTheir engine is called source.
The collection of libraries valve release to use steam (the piping, if you will), is called steamworks.
RightHandOfIkarosWould have been cooler if they named their engine Vapor instead
Instead the story is that the source engine was located in the “Src” directory in their Visual Source Safe. And the Half Life 1 engine was in a separate branch named GoldSrc because it was about to ship real soon, and they needed to keep changes to a minimum.