Best is root, remove bloatware, use performance goovernor when you start playing, maybe use one of mod. If you delete unused bloatware apps, phome will speed up.
. Im using newest. 167 and playing games smoothly, im using No Aggresive (4th mod).
For downloading games im using Dolphin browser, and i mounting it with FolderMount. With Link2SD you can uninstall system apps and move to system better using apps. (Like FB, Messenger, Root Browser better than Default File Manager,..)
But best is experiment and try what you like.