The premise of the game is wonderfully simple: you're in an AC-130H Gunship and it's the End of Days. You're providing cover fire for humans as they run for the safety of a bunker. You must kill zombies before they enter the bunker. If you kill three humans or if a zombie enters the bunker, game over, man.
I've put some time into this game in the last week, playing on the toilet until my legs go numb. I'm doing pretty well. I consistently kill over 1000 undead before some stupid human runs into a 105mm Howitzer shell. Now I'm paying it forward. Enjoy my meager strategy tips.
Tip 1: Touch and Go
|"It bodes well for me that speed impresses you." -Chandler Bing
The first thing you need to know is these zombies NEVER stop. They took that Chili Peppers song lit'rally. And they spawn in half a dozen places. So, you need to pepper the ground with shells when you see zombies, and then move your view to other areas. If you try to be Johnny OCD and kill every zombie out of a group when you see him, you're going to let 30 more sneak up to the bunker. My success comes from dropping some lead and moving on. If a couple zombs don't drop from that, I can always swing around in a bit and finish the job. The key here is speed and constant movement.
The game warns you when zombies get close to the bunker with red warnings, so use that to your advantage. Skim the outer rim early on, and shoot the junk out of groups of zombies, not worrying about 100% kills. You only need to ensure the zombies die BEFORE they enter the bunker, so you have time. Spending your effort on cleaning up a whole mob of these things on the outer edge of the map--only to have a group of 'em encroach on your bunker elsewhere--is akin to throwing out the baby with the irradiated bathwater.
Tip 2: Smart Upgrades
|Careful reviewers will see I didn't follow my own advice.
The beauty of this game is the upgrades system. Every zombie you kill (and human who finds himself in your bunker) earns you points which you spend on upgrades. You can upgrade your three weapon systems, increase the points you earn from killing zombies, invest in a last-resort bunker defender bomb, and increase your radar range. A huge key to your success is in how you prioritize these upgrades.
First and foremost, I recommend pumping up your Zombie Bounty (points per kill). Doing this early in your career is like recognizing the value of compounding interest. Get in on the ground floor with this so that every round you play is more fruitful (and thus easier to get the other upgrades).
The next tip I have is to always prioritize the reload (and cooling) rate of your weapons. Powerful weapons are no good if you're waiting for them to come back online.
And you should be careful not to upgrade the damage radius of your 25mm Gatling Gun. This gun is best served for sniping zombies grappling with humans (if you're into that kinda thing...see below). And each time you upgrade it's damage radius you have to recalibrate yourself to get comfortable with sniping so close to warm bloods.
To recap: upgrade zombie bounty, then reload, and scale back the damage radius of the 25mm. Everything else is up to you.
Tip 3: Humans Are Expendable...
|"How can you shoot women and children?!"
"Easy, you just don't lead 'em as much."
...at least two are.
So far as I know, there is no penalty for killing the first two civilians in a round. It's just that pesky third that jumps in front of your hail of bullets that causes Sarge to pull you out of the hot zone. Use that to your advantage! If a helpless soccer mom running for safety is the only thing stopping you from thrusting a 105mm round down the throats of a score of zombies, and you've killed less than two already, don't hesitate (provided you need those undead deader than dead on the quick. Remember Tip 1 and consider coming back later.)
While on the topic of coming back later, you need to be willing NOT to snipe zombies just because they're snacking on a human. Humans eaten by undead out there on the battlefield don't count against you. So, if you can stomach it, and you don't want to risk having that human die by your trigger finger, just let the zombie eat him/her and blast that zombie after. Remember: Touch and Go.