Crashes all the time on iPhone 5s

I used to play HS on my iPhone 5s without issue. Mainly play on PC, but when travelling/camping/etc, my mobile worked just fine. This has not been the case for quite some time now. I can barely enter a game without game returning me to phone home screen. Is this game just not viable on my iPhone 5s anymore? Is it problematic on all iPhones, or just older ones? Do I need to go Android next phone to be able to have problem-free HS gaming?

All feedback appreciated.

I cannot even start a game anymore, always crashing at startup on my iphone6+!
Did you get it fixed?