Duke Nukem Forever's initial release estimate (as announced on April 28, 1997) was "mid-1998" [source: Wikipedia].
This is a really tough one to put a date on, because I'm quite sure the announcement was never meant to be considered specific. The best I can do is pose the question this way: "What is the last day of 1998 that would still reasonably be considered 'mid-1998'?".
We generally break the year up into four sections; businesses do it by fiscal quarter, and outside of work we do it by seasons. Given that, if I define the second and third quarters as the "inner half" of the year (in other words, April through September), then the last day of "mid-1998" would be September 30, 1998 (with a valid release possible until 23:59:59 in the "last" time zone).
Duke Nukem Forever released on June 10, 2011 [source: Wikipedia], giving it a final vaporware duration of 400,370,401 seconds.
There are separate dates listed for "worldwide" and "North America" releases, and I'm not sure exactly what "worldwide" means in terms of time zones; given that fact, the most reasonable determination I can make is that the game was available everywhere in the world besides North America on June 10.
| Event | Relevant time zone | UTC | Epoch (UNIX time) |
|---|---|---|---|
| Initial release estimate | 1998-09-30 23:59:59 UTC-1200 | 1998-10-01 11:59:59 UTC | 907243199 |
| Actual release | 2011-06-10 00:00:00 UTC+1400 | 2011-06-09 10:00:00 UTC | 1307613600 |