if u leave the game open all the time, which means not locking your screen at all, the phone may get a little warm. but if u only unlock your screen to play every few minutes, I think the power consumsion is quite manageable. I also regularly close out the app from app switcher and restart the phone, maybe once every 12 hrs or so. I find that by doing this the power consumsion is much more manageable. whenever there are graphics, whether simple or not, the power consumsion will be high. it's similar to if u were to leave your phone on watching a long video on youtube, the battery won't last long either. as many people have misunderstood, having screen curtain on or off will not affect your battery consumsion at all. if u want, u should set your brightness to 0 percent, turn blue tooth off, and also put phone on low power mode. hope the above info can help in some way. my phone is a iPhone 6s, which has been with me for almost 2 years now, and I can still play ck probably up to 4 to 5 hrs nonstop before battery reaches below 10 percent.