However pwede mapababa kundi mo gagamitin for the meantime (Pahingahin mo). I suggest buy a new phone that have a features of hibernation of apps while playing (like Samsung High End Phones) May app na greenify para disabled muna ang mga ibang apps ka while playing. 
Kahit naka-low papz eh longer time ka naman maglaro balewala dinnormal naman uminit ang smartphone mo dahil gumamit kasi ng cpu at gpu power, if you want to reduce heat, reduce mo din ang fps setting ng game, graphics mode to low (if exists)
Reducing but not enough.