Hey, thanks for trying out the game and for your feedback !
When served, the customers were supposed to be pushed back (and disappear if they reached the door) like in the original arcade game.
But I mismanaged my time and didn't get time to implement these functions (and some other gameplay stuff)... ^^'
Without these parts I ended up using a basic higher level => faster spawn rate. It did end up making them cluster more and more if they successively spawn in the same lane.
If I keep working on this game, it will definitively get addressed !
Have a good one ! o/