That means the code is incorrect which isnt the case as we know it works.
It also could mean the file you downloaded had become corrupted while downloading.
Compilation error
Compilation error refers to a state when a compiler fails to compile a piece of computer program source code, either due to errors in the code, or, more unusually, due to errors in the compiler itself. A compilation error message often helps programmers debugging the source code for possible errors.
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Only if you can, or have the time.
The only possible thing I can suggest is uninstalling/deleting all files to do with FW on your phone. Meaning not just uninstalling but in a file manager such as ASTRO "Download" or even the phones browser by pressing the menu button and scrolling down to "Downloads" and deleting all previous downloads off that particular phone.
Download the Non-Google Play version. (DO NOT PRESS INSTALL AFTER THIS STEP)
Exit out of any screen you are in, go into ASTRO and find the file you have just downloaded found by these steps;
Open ASTRO 》Manage My Files 》Download 》Find a file named "FactionWars_smalltex........apk" 》Press on icon to bring up a menu 》Install.
This will use a seperate 3rd Party App to install the game as it shoud be normally. (Not using Stock Installer built into phone)
(Other method, try downloading from PC uploading onto phone, then going into ASTRO as above to install the app. (This has worked for many members/phones, and was the only way I could play using my HTC Desire)
Good luck and let us know how it goes (: