It may have taken 15 years but both Half-Life and Counter-Strike 1.6 have been released for Mac and Linux users.
While the clamour for their release may not have been deafening that quiet may be more potent evidence of Valve's commitment to the other platforms that if it had been loudly desired.
More below (though only a little).
That Valve are going through their back catalogue (and way back at that) is a welcome sign that they intend on supporting both the apple and the penguin-powered computers.
Both games are available for sale in the Steam store, so if you've been sitting, ageing at your desk till this point, make those dusty joints click here.