That's not five engine switches.
1997, originally slated to use the (then) state of the art Quake II 3D engine
1998 arrived (June, specifically) 3D Realms announced they were changing 3D engines to Epic's Unreal engine
As I said, they switched from Quake II to Unreal. That is a single switch. Okay, that's one so far.
1 Initial moneys spent. This is necessary.
2, engine switch, moneys spent. Maybe necessary?
1999 came and went, Duke Nukem Forever saw another engine change, this time to an updated version of the same Unreal engine they were working on.
Updating an engine and switching is definitely not the same thing. Still one engine switch so far.
3, as the update would cause a halt in productivity, and is a needless deterrent. Plus moneys spent.
2002, 3D Realms hired new programmers, and decided instead of switching to another 3D engine, they would just develop their own, making this the fourth engine change
Well actually, that would make it the second engine change. Even if you count the update as an engine switch, this would be the third.
4, more moneys spent. More jobs filled.
2004, GameSpot.com revealed a rumor that Duke Nukem Forever had made its fifth 3D engine change, this time using the Quake III engine
First, this is a rumour and a baseless one at that. Second, Why would they switch to an engine that was released around 1999 during the year 2004, especially after basically making their own engine?
5, rumour or not, I'll stake my credibility on GameSpot.com while drunk if need be to sway this argument that could, arguably, last Forever.
I count 5 engines. An updated engine is essentially a new engine, IE: Rpg maker 2000 to Rpg maker 2003.
You're right though, not 5 engine SWITCHES as I mistakenly typed, just 5 engines. Rumour or not... We can assume after THIS long of development and changing engines even 3 times... that they are a frivilous company. So, yeah, my point is it's little wonder that they're out of business.