The video/audio is broken on mobile safari.

You can’t preload them, seek them, concurrently play them, change the volume of them using javascript. It’s likely that there will be intolerably indeterministic lag after you issue the play() on audio objects. 

You want to have instant audio feedback to user input, but you will get that in several seconds later. That makes iOS web games silent––those html5-based games can’t play the sound effect in a stable way.