Game Killer APK (or GameKiller) is also an android program to modify coins, gems, etc of android games by using technique of memory changing.  Gamekiller has been downloaded by more than 10 million users worldwide making it among the most downloaded app not available on Google Play store.
Game killer is a powerful yet simple to use, supports maximum variety of games and is compatible on latest android variations; Lollipop and Marshmallow.  It is possible to download Game killer freely with no survey as well as read detailed step-wise procedure on utilizing Game Killer on this website.
1: Your Android device must be rooted

In the testimonials left around the internet, this first step is the one that trips up users the most.  Rooting an Android device is not necessarily a beginner-level task, but Game Killer requires root access and won't operate without it.  There are many apps available on the market to root on a device, but if one of these not work for you, a quick Google search will yield guide Android rooting instructions.
Generally, one knows if their Android remains rooted.  If you're unsure, however, launch Game Killer will result in a telltale 'insufficient permissions' mistake.

2: 'Unknown Sources' must be turned on

Still another hang up that new Game Killer users may encounter is an 'installment blocked' mistake.  Simple to repair, this requires you to flip on the 'Unknown Sources' choice inside the device's 'Application Settings' (or 'Security') menu.
A caveat: empowering installation of programs out of 'Unknown Sources' is a significant security risk.  For security, only install trusted applications downloaded straight from the developer's website.

3: Game Killer only modifies offline games

Bummer.   *Game Killer is unable to modify games with their information stored on remote servers so, if a game needs an online connection, this program won't work for them.  A game must store its score/life count in resident memory for Game Killer to get and alter it.

4: The tutorial is not optional

Yes, you read that correctly.  The tutorial isn't optional.  If you're to have success changing life, score, or coin values, Game Killer's tutorial needs to be followed to the letter.  Confused, 'how can I do this?'  Testimonials are second only to reviews unaware of the main requirements.  Save yourself and easily avoid this by reading the programmer's FAQ.

It is true that there is a lot of prep work involved in getting Game Killer ready to go on your Android, but don't let this be a deterrent.  Once set up, Game Killer works flawlessly and as promised.  As the final word in this review, there is yet another recommendation: Enhance your learning curve and also experimentation with Game Killer app in a easy game program first.