Sure, Half-Life may be nearly 15 years old, but that doesn’t stop today from being a joyous day for fans of one of the greatest first-person shooters ever created. At long last, Half-Life is playable on the Mac — an OS X-compatible version was quietly released on Steam today. Sure, OS X wasn’t even a platform when the game launched, but we’re not completely surprised by this release given the love that Valve has given to the Mac over the last few years. While the game’s Steam listing still lists it as Windows-only, we’ve just downloaded it and verified the game works just fine on the Mac. Half-Life might look a little dated after all these years (hence last year’s long-awaited Black Mesa remake ), but it’s still a highly-enjoyable,..