Hey! I made OUTLAW MAYOR PANIC! this last weekend, where you play as an outlaw mayor who outruns the law while building a city. The idea was to cross pac-man with sim city, but my ultimate goal for this LD was to utilize a 3D technique I see a lot of GameMaker devs use!

The effect layers 2D sprites in a way that makes them appear 3D, and was most prominently used in NIUM by Moppin and Nemk, but it's also used by other really awesome developers like @Salman_Shh @iampinqu and @like100bears.

It's not a terribly difficult effect to pull off if you know how to sort sprites in the engine you're using, but it gets a little tough when you add in camera rotation (thanks @elanti for the help with that math!). It was pretty easy to accomplish in HaxeFlixel, although the tutorials and help I found for GMS didn't really parse well.
Creating the assets for the game was a tiny bit challenging, because you need to create a sprite for each layer of an object, and while you're editing the sprites, you don't really see what the end result is going to look like until you plop it down in the game (which makes this one of the first LD's I actually got a lot of coding done before making art assets :P), but despite that I think the novelty of the effect allows you to get more mileage out of every object that you create, so it worked out well!
I was pretty happy with the effect, and I'll probably use it in some upcoming projects because it was so fun!