I have been tracking the series of events that covers the 14 years of the making and finally it's coming out internationally on 6 May. Pretty excited to see it coming and tearing aliens apart!
The 14 year hiatus is primarily on switching of game engines, the compulsion by 3D Realms (George Broussard in particular) over many things to toss into it (the core issue is interactivity unsurpassed) and finally, the lack of money which resulted in 3D Realms closing down in May 2009. Lawsuits by Take Two against 3D realms over the incompleted project put that on hold and finally the resumption of the project towards its release....
The first thing is primarily on the game engines. In 1997, it started with the Quake 2 engine (a.k.a Id Tech 2) - it was good, but Quake 2 at that time could not perform outdoor environments. In 1998, it was scrapped for the Unreal engine, which allows that capability. But in the subsequent years, Unreal engine evolved 3 times, and 2008 it was Unreal Engine 3. So virtually, the game content had to be moved to utilizing the new vast improvements of Unreal Engine. Virtually most of the content had to be replaced with newer content. I thought, with a PC Gamer magazine cover of the game in 1999, I thought it would be out as early as 2001, but it didn't really happened.
I have read about Broussard's obsession of never releasing a bad game in favor of taking time and perfection to getting all correct down to the bottom, and that includes the interactivity (e.g doing some crazy things like taking a leak in the toilet, using the drawing board and all those freedom of interactivity inside it. But in the process, ex-3D Realm alumni now Gearbox CEO, Randy Pitchford said that Broussard funded 20-30 million dollars of own money over that period but couldn't get it done. Quote: "He (Broussard) was committed to the point of insanity."
So in May 5 2009, 3D Realms closed down. The lawsuit came in a week later and finally a year later, at the Penny Arcade Expo 2010 everyone got surprised with a work-in-progress build that is being played by the visitors there. Confirmation on Gearbox taking over the rights to the game came in on September 2010 on a press release. At that time, they said that most of the game content has been completed and virtually the next few months is on polishing and tweaking, before the release date was announced a week plus ago.
The above video is a live demo taken from Amsterdam gaming convention a few months ago.
14 years is long the wait.