There's a ton of stuff that comes with Blitz3D (when you buy it) that qualifies as awesome demos.
Personall, two demos really sold me on Blitz3D:
Mark Sibly's Castle Demo (would be nice if the content graphics were prettier, but it achieves an awesome amount with a tiny bit of code).
AGore's BirdDemo
From these demos it was pretty clear to me that Blitz3D was capable of delivering pretty much any 3D game I wanted to design.
I think demos based on these (but with improved content) would serve as great advertisements.
Personall, two demos really sold me on Blitz3D:
Mark Sibly's Castle Demo (would be nice if the content graphics were prettier, but it achieves an awesome amount with a tiny bit of code).
AGore's BirdDemo
From these demos it was pretty clear to me that Blitz3D was capable of delivering pretty much any 3D game I wanted to design.
I think demos based on these (but with improved content) would serve as great advertisements.