3D Flash engines seem to be popping up everywhere at the moment. [Although I wouldn't call that a bad thing] - Each one tends to take a different approach, do a different demo to distinguish themselves. Take this for example, a very impressive looking offering from Alternativa3D;
Papervision might have a lot of features and a large fan-base, but I have yet to see such a visually impressive demo [as this one]. And they've already sorted the first-person movement and collision detection. It's also very cool that the demo seems to 'quickstart' - loading low-res textures to get you going as soon as possible, and streaming in higher res. ones while you play.
Progressive textures - how cool is that? (above)
Of course, there's visual trickery going on here - the fantastic visuals are more down to excellent textures, rather than dynamic lighting or raytracing. But that doesn't mean that the Alternativa3D team doesn't have that on their 'to-do' list...
So, what are you waiting for? Go check it out at alternativaplatform.com.