Duke Nukem Forever is still a thing and it's a thing that is apparently actually happening.
The playable demo finally arrives on June 3 but only if you've pre-ordered the game, which grants you access to what the studio is calling "The First Access Club." Here in the US, Amazon and GameStop are the retailers handing out the codes needed to be first in line for Duke Nukem Forever's demo.
In all likelyhood the demo will become available for everyone else soon after. I've pinged the game's publisher, 2K Games, to find our when, if and how that will happen.