I'm a Duke 3D fan, owned it as a kid on the N64 and PC. I know I would probably loved it, much in the same way I loved Half-Life. I don't think being a Duke 3D fan means you'll not accept anything that isn't Duke 3D. Everyone knew it wasn't going to be another Duke 3D ala doom clone, especially with game likes Quake 2, Unreal and Half-Life that started to change the formula of the FPS. What draws people to Duke is the borderline parody story, seedy atmosphere, and his goofy yet lovable personality. The leak showed there were secrets and carry over features from Duke 3D including the jetpack. It seemed like DNF was going to be to Half-Life, to what Duke 3D was to Doom in a way. And keep in mind, when this trailer came out, the concept of the retro FPS wasn't really a thing yet. Everyone who had a PC and read about the DNF 2001 E3 trailer in a magazine or website was still using a 9x OS like 98 and a DOS game like Duke 3D was still being sold alongside other PC games at game/electronic stores since it was still relevant, popular and compatible. People weren't as pessimistic and jaded about the industry like they were in the tail end of the 2000's. Even a game like Doom 3 caused super hyped by Doom and FPS fans despite the 2001 and 2002 demos clearly showing it was going to be a slower horror based game compared to its run and gunned predecessors.