Contract Killer Zombies 2: Origins (stylized as CKZ Origins) is much different than its predecessor, but it’s one of the top zombie killers on any game system this side of the Resident Evil series, so the fact that it’s free for the iPhone is rather impressive. One thing that has not changed, however, is the microtransaction and double currency system. The two currencies are cash, which is the more common of the two, and gold, which is more rare and valuable. You can earn them without having to pay any money, though.
One way to earn free gold is to play for the awards and goals. To check out the awards and achievements, go to the trophy icon in the main menu, and swipe up and down to see all of the missions that you have to accomplish. They’re difficult, but goals are easier to achieve. Go to the “goals” menu in the upper left part of the screen. Complete them all for a new set of goals and some free gold.
Beating a story stage will earn you free gold, as well, but the best way to earn free gold is with the Tapjoy offer wall. Click on the “Get Free Gold” button, of course, to get to the offer wall. Sign up for Tapjoy and you can do any of the offers that you want to. Go to Tapjoy.com and login, and search for offers related to CKZ Origins, and you will be able to find even more free offers which you can do, most of which simply involve downloading, installing, and running other apps.
The only known way to get free cash is to beat mission stages. You can trade your free gold for cash if you want to, technically making it free cash, but there’s much better to spend the gold on, such as better weapons.