Where can I get the source code for the vortex demo on the site?

We did not include this effect (yet) because the graphics used are part of our upcoming game. The effect will be included once the game has been released.

However, we posted a brief description of the effect on our Video Showcase Page that explains how you can achieve this effect.

The technique is quite straightforward: take an emitter, attach one or more particle types, set the emission shape to ring type and set the "face emitter" property to true. The particles then start outside the emitter at a given radius and move towards the emitter.

Then simply place your emitter in a group (all particles of this emitter will then be drawn inside this group) and steadily rotate the group. This will rotate all particles at once, while they are moving to the center, which creates a vortex like effect.

That's all, it's quite simple.