Hi,

I've knocked up a quick interactive thingie to demonstrate my proposal for a visual effect for presenting/hiding z-layers as the Hero moves in Z:

Live Demo

I like this effect because:
a) fast enough to not be distracting
b) not canned, the effect maps directly to the player Z position
c) reinforces the metaphorical visual 'stacking' of the layers
d) will look really cool on stairs

If anyone has different ideas, you could clone the github for this thing and tweak to demonstrate your idea.

https://github.com/lakmeer/handmade-z-transition-effect/tree/master

Sorry if the code is madness, it's just a sketch I made this afternoon.

Cheers,
Lakmeer