Many Dead Trigger users who paid for the game are posting angry one-star reviews on the page because the game is now free. Madfinger, for its part, says it was forced to stop charging. Here's the company's statement, released on Facebook:
Regarding price drop. HERE is our statement. The main reason: piracy rate on Android devices, that was unbelievably high. At first we intend to make this game available for as many people as possible - that's why it was for as little as buck. - It was much less than 8$ for SHADOWGUN but on the other hand we didn't dare to provide it for free, since we hadn't got XP with free-to-play format so far. - However, even for one buck, the piracy rate is soooo giant, that we finally decided to provide DEAD TRIGGER for free. Anyway - DEAD TRIGGER is not FREEMIUM, it always was and still remains FREE-TO-PLAY, that means, all players are able to play it without IAP! We stand up for this statement, because all members of our team are playing (and enjoying) DEAD TRIGGER without IAP.
Piracy is a serious problem for both platforms, but the general consensus is that the issue is much more serious on Google's Android than it is on Apple's iOS. After you add fragmentation into the mix, many app and game developers find it more difficult to succeed on Android compared to iOS.
There are many reasons given for this large gap. Some say it's because Apple users are simply more willing to spend money than Google users. Others believe that since Android has a larger market share, it also has a larger group of pirates.
I think the problem largely comes down to a much lower barrier to entry: on Android, you can sideload apps after changing a setting in the operating system, while iOS requires you to first jailbreak the operating system. Thankfully, paid app encryption is coming to Android. We'll see soon enough if the feature makes a large enough impact.