Thanks for the information, we will keep in mind for the future.
At first, we just sent a report to the game and wrote directly to support, but there was no response. Therefore, we decided that we need to use the DMCA service, since this was mentioned when sending a report to the game.
And we paid because the DMCA requested payment to continue the process:
We have reviewed your case and the infringing URL listed. At this time your case would cost $199 and in order for professional staff to proceed with your takedown request, we will need you to pay for this case using the PayPal or Stripe buttons on the upper right hand side of this case detail view - above. Once payment has been received your case will be immediately processed.