turn most of the graphics to medium and the craft reflections and stuff to max if you want higher quality. you can also turn on all the image effects except reentry heat trails, for some reason the game crashes when it’s on

anyway with these settings my iPad Mini works fine, just 7 to 22 FPS (20 FPS most of the time)

You basically want all of your graphics settings at low or off. Definitely turn shadows, reflections, and water completely off(it doesn't completely remove them from the game, but it uses waaaay less RAM). The only graphics settings that kinda have to be high are for structures otherwise they won't display properly. You can also leave your physics settings at medium or high, but you might want to go with low depending on how you feel