I was able to beat it by myself with Steve Carter at about level 30 (probably between 30 and 32). I have is Critical Hit Rate Maxed with most of the rest of my AP towards Maximum HP. All three Critical equipments were-um-equipped, and used the M4 and GDE (GDE never used).

The pain in the ass is that most of the timing is luck, you usually hope that you don't end up circling The Origin (boss) and not seeing a single eye open. My strategy for finding the open eye is staying near one eye. If you move a little bit to the left or right, one of the adjacent eyes will be in view. If none of them are open, just wait (sucks, I know). It's probably a good idea to not stand in front of the eye as you wait, 'cause it might not open, though I'm not sure.

Once you have an eye open, stand directly in front of it and let the bullets fly. Now the difficult part here is managing the minions. When I see them coming from the right, I'll strafe left trying to aim so that I spray both the eye and minions at the same time. Same with the left (obviously). When they come from behind, I'll wait until they are just about on top of me and strafe back and around them, always aiming at the eye. This way, again, I'll hit both targets with one stone.

What you have to look out for is that this strategy counts on you getting injured. You take some hits when you maneuver around minions; sometimes I'll even let those little red brains just explode on me with out moving.

Hopefully this will help you beat the challenge. Obviously, having ammo and health boxes placed near The Origin is huge, but luck has a lot to do with it also.

Good luck and happy hunting.

As I have a first generation iPod touch, no multiplayer for me. Though I am proud to say I beat all thirty missions with 29 completed challenges (can't get the final level).

My only complaint about the game is the almost completely top-down camera angle. In the second 10 levels, it makes it very difficult to distinguish trees from bushes which can cause the character to get lost behind a tree easily. If there are zombies (namely the dogs) in there, it's pretty much lights out if you can't move.

Still, this is a definite 5 star game for me. And even a highly recommended purchase at $2.99 when the price increases.

Basically, get the M200 (most expensive sniper rifle). Then, buff up on health (I used maxed out Taza + vest + helmet). Reload-time gloves are a good choice for last equipment slot.

With that setup, you can definitely win the level. For the 180 sec challenge, you need a bit of luck with the pickup spawn points and eye sequence. The real challenge is deciding how much you can afford to ignore the critters and just take the damage. Remember, you can shoot further than you can see, and you can angle your shots at the eyes so you hit some of the critters attacking you.

I've done it twice, but the second time I used the power equip I won the first time around, so it doesn't count.