Given is an image of a noise of coloured dots, whose near-periodicities suggest it's a random-dot stereogram. Viewing it as one shows the following image, reading RGB.
Taking the RGB values of all the colours in the original image gives you a collection of triples, i.e. points in three dimensions. The 3D interpretation is clued obliquely by the title (Mario Clash was the first stereoscopic 3D Mario game), and by the fact that stereograms also encode 3D images. Here's what all the points look like together (Jmol applet, script by Sage; give it a minute to load):
In case that fails, below is a still image of the point cloud from one particular direction. As you can see the points form a JACK O' LANTERN, which is the answer. (The 3D model from which our point cloud was derived was from the Gamma group collection at INRIA.)