I will warn you - doing so may actually be a bad idea.
There are "fake stores" out there that may give modified apps - ones that can steal passwords, credit card info, and do all sorts of things to your device.
I am hoping for a list of "official supported markets" to come out, but in the mean time, just be smart about it.
You should only download apps from trusted, reliable app stores.
You should not install if the app requires permissions you do not want it to have.
For the current version of FT MMORPG (6.3.0), the Google Play version only requires the following permissions:
In-app purchases
Photos/Media/Files
- read the contents of your USB storage
- modify or delete the contents of your USB storage
- read the contents of your USB storage
- modify or delete the contents of your USB storage
- view network connections
- full network access
- control vibration
If you're trying to install a version of the app from another source, and it requests permissions other than these, you may wish to reconsider the idea of installation.
Be careful out there people - the internet can be a scary place.