Black Ops 3's Nuk3town map is going free for all players. Previously, the fan favourite was confined to a pre-order bonus, and, for UK boxed copies, a Game-exclusive pre-order bonus at that. Given that Game's PC selection is unlikely to tempt a Steam user, I can't image it was busy on PC.
Nuk3town will be included in the main map rotation across most game modes, and for the first week Treyarch will be running a Nuk3town 24/7 playlist. Accompanying the map is Nuk3town themed Weapon Camo, three Nuk3town themed weapon reticles and a Nuk3town themed calling card.
There was some confusion as to when the patch (1.08) drops—Activision announced that it was live on all platforms, Steam users said otherwise—but now Treyarch's director of development is indicating we should expect it later today.