Zombie Ace is an excellent new auto-scrolling title from Hothead Games, who also brought us a similar title in Sea Stars, and were responsible for porting the excellent Machinarium to Android. It's a clever and odd little game with a lot of creativity, nice art, and addictive gameplay. Unfortunately, it's also a bit too heavy on the in-game currency and upgrades, pushing the in-app purchases quite a bit. Still, it's not as bad as most freemium games.
I would imagine one big issue for any successful zombie apocalypse would be spreading across so much land on foot. In order to expedite the infection of the world, it's up to you as a zombie pilot to fly and drop off loads of zombies in various cities, all while the military does its best to shoot you down. All the while, you can throw zombies at the enemy planes to down them, dodge various obstacles including a yeti, and pick up coins and cool power-ups.
The gameplay is your basic flying auto-runner fair, with touching the screen to ascend, and not doing anything to descend. The challenge in the game comes from your limited fuel supply, making it harder to get to farther off cities. This is compounded by the upgrade system. You can use zombie dollars and brains to purchase better plane parts and pilots, but after a little while, they seem very overpriced. You essentially hit a pretty big grind for currency, which can feel frustrating, all to push the IAP currency. Still, even with the grind, this game provided me with hours of fun.
The art style is rather unique, with bold lines and background patterns reminiscent of a comic book. The background music is pretty awesome too, and the game is bursting with personality and charm. I love zombie games that let you play as the zombies, and the goal of infecting all of the United States is just awesome. I definitely recommend the game, as long as you're ready for the pushy IAP. It is totally free, after all.