Cool raineffect?

Can you tell me how is that cool raineffect done in that one ghost hunting thing? Not the rain itself but when there is water on ground?

It uses a black and white sprite(most likely a white ring on a black background) with the "Distort" effect. Then you could just have it scaled up a little bit every step to make it look like a moving ripple.

But how is the sky reflected there?

I think that, on the layer with the ground, there are sprites with the erase effect that will erase what's on that layer, and then there's a sky background on the layer underneath that. I can't remember if it's done exactly like that, but it's similar.

EDIT: I whipped up an example demonstrating this effect real quick: Erase Example

Hope this helps.

Ah ok thanks