On mobile, you just swipe in the direction you want to move (e.g. swipe up to go up). You can also queue the move ahead of time. So even if you are nowhere near the intersection yet, you can swipe up and trust that the ghost will automatically turn once it reaches the intersection.
Just like the original Pac-Man game :)
Could be my shitty phone, but the swipe lag is huge. I can swipe ~1s ahead of time and still miss a turn.
I don’t think you can take a turn until you hit a wall?
I don't think so -- I managed to turn while on long straights, but nearly always after the turn I wanted to make.
I think what's actually happening is that the game only counts your swipe as an input once you lift your finger off the touch screen.
You can kind of get away with that if you're implementing, like, 2048 (although the official version at play2048.co doesn't do this), but it feels way too unresponsive to be usable in an action game.