Making a “minimalist” poster with 8-bit NES sprites is tricky, since the sprites are already pretty minimalist to begin with. Solution: make everything black (sans one question mark). Also add some clouds in there for good measure. The blocks are in there to make it clear that this is from a Mario game; otherwise it would be hard to tell that those big black things are giant mushrooms.
I took a graphic art class back in high school, and I really wish I remembered anything from it. To be fair, we mostly used non-free programs like Photoshop, and I made the above picture with pixlr (I only have Photoshop on my old, slow computer), but many of the tools are the same. Maybe this would take even longer to learn without that class? This wasn’t too hard to make, for the most part, but I hadn’t realized it would be that small. Oh well. (EDIT: apparently that’s just for this page – click on the image and you get a full-sized one. Huh.)
Anyways, the Mushroom Kingdom seems like it might be a fun place to visit, if you can get past all the killer turtles.