What if Levi had access to Model OX from Mega Man ZX? 

Levi would have obliterated Zeke by now and saved the world.
Just for shits and giggles, I modified my Omega Zero mod so that it would be Levi wielding Omega's Z-Saber and Z-Buster. Also, Petra with access to Model OX could have ensured her survival against the Female Titan. Probably. I dunno.
Oh, and I had modified my old bad-guys only patch for my Lizard Squad so that all enemies would fire projectiles, just as if you were playing a side-scrolling shooter, like Metal Slug (obviously).