> Giving things away for free is not the same as making it public domain or relinquishing your (copy)rights.

Obviously. But it does kill the usual "piracy is bad because companies lose money" argument - especially for a 22-year-old game.

> Source available is not the same as open source.

Obviously. But it does show that Valve is more interested in preserving old genre-defying games for the general public, rather than milking every last cent of revenue out of it.