tinyE: I reluctantly joined Steam a year or so ago. It's bad but it's not THAT bad and if you really want to try DK Forever I say go for it.
You can play everything in offline mode which is what I do. I don't remember the last time I actually logged into Steam. The client starts but because I have the default to Offline mode it does so without actually logging
in and I don't need an internet connection.
I don't hold it against anyone who refuses to try it because Gabe is a 300 pound butthead, but desperate times call for desperate measures and Duke evidently hates GOG. :P
I already have a Steam account and a bunch of Steam games, and unless I get them dirt cheap, I am not keen to get any more, especially if I then have to buy it again on GOG later, when it does eventually become available.
For me, this is not just about Duke Nukem Forever, but the whole series. And it is also about full control of the games, that I REALLY OWN ... not pretend that I own. If I can't easily do whatever I want with them whenever, then really, I am not prepared to spend much on them .... plenty more out there, more deserving of my money.
P.S. And because i am indeed a Good Old Gamer, I do have boxed editions of many of the games I have bought updated versions of from GOG, including some Duke Nukem. I am talking the large boxes, not DVD case size ones. So while I don't mind paying a second time to get DRM free and updated versions, I balk at doing a 3rd purchase because I foolishly used Steam second.