Let's illustrate that our game can handle ANYTHING YOU CAN IMAGINE by showing the most generic tropes floating around in space in...bubbles.
Or maybe quadrants?
Hey that genres-in-quadrants thing that GURPS did above seems like a good idea! Right? Right?
Okay, what if we scrap the quadrants and just mash it all together? Oh, no, that's just a god-damn mess:
Okay, okay, let's simplify then. Less is more, right? Right?
Maybe simple will look better if we do a color gradient? Maybe?
Okay, that didn't work. Maybe if we make the cover look like the label of a body-building supplement?
Hmm, da Vinci is cool, right? Gamers love da Vinci!
This is what is looks like when you lose all hope: