Waterfall textures

I'm not quite sure, but.. right next to the big rock in the center seems to be a pattern that repeats (the faster texture layer).

Somehow the layer seems to move very, very slowly perpendicular to the flow direction, because this patterns moves after 3 or 4 iterations closer to the rock.

From that I'd guess they used static textures.

Perhaps just try to implement this with static textures first. I guess, having nice textures does the trick, here.

The water looks like a deforming mesh with a texture that moves with it(local scale), overlapped with a brighter blue texture that moves based on a global scale.

You could deform your mesh with trigonometry or with some engines thy give you a deforming mesh(sometimes known as a Lattice mesh), but a few textures should work(You will need bump maps/normal maps for waves) and run faster without people knowing or caring to much.

My guess would be a simple animated mesh with a mostly transparent animated blurry texture, and particles for simulating foam/drops with a number of slightly different static textures (this texture would be something like little splats blurred in one direction to give the impression of motion blur when particles move).

Particle overall alpha would likely be a function of particle speed and its face normal, so there is more foam visible where water is falling, hits rocks, and floats around them. Very little foam where water is calm, up at the edge, and half a meter from where the water falls into the lower body of water (normals pointing upwards to the sky here).

The thread offers to download the file. I don't trust downloads from unknown sources.

Oh it's so simple a static mesh with moving texture ( of course alpha blending)

multi Textrue blending is very good for this kind of things.

but If I was I add some distortion of mesh position this water fall, it is not fit to Halo, too old technic and ugly.