If you really want to go after them no matter the cost, you can ask for a habeas data through the court to track down the IP address of the perpetrators, the habeas data would be able to compel Apple and providing the IP address of the devs at the time they registered and uploaded the game, if the ISP is within the UK another Habeas Data would work but not even that is a guarantee that you'll get what you want. At the end of the day, you'll just have to accept the loss and end it at Apple removing the copied games or pursue this to the bitter end. If the perpetrators are outside the UK the expenses would rack up and won't be worth the presumed 60k$ at the same time the damages you'd receive may not even add up much unless you can make the perpetrators pay for your litigation fees.