Default Rooting and my Galaxy S5 problems

hi all, new to this forum, figured this place would be the best place to come to get help with my GS5 and some issues i am having with Rooting and trying to get Apps to work.

ok, so i rooted the phone, have SuperSU, checked to make sure it is rooted, says i am, but i can't seem to get the modded google play store to install, or an app i wanted to use to work, this being Game Guardian, its a hex editor, and my legit owned FF5, keep getting the "is your game dead" message when searching for values, and the Modded google play store just won't install at all.

any help with this? thanks to anyone who can.