Fortnite is more about in-game battles, but its creator is in conflict offscreen, too.
Epic Games is unhappy with Apple over the payment system on its app store and control over downloads.
It took the fight to a U.S. court, but couldn't make any progress there, so has now brought its case to antitrust regulators in the European Union.
The two firms have been in a legal dispute since August.
It began when the game maker launched its own in-app payment system.
This was designed to get around Apple's 30% fee on some in-app purchases on the App Store.
Apple responded by kicking Epic's hugely popular Fortnite game off the App Store.
Epic Chief Executive Tim Sweeney said Apple's control of its platform did not make for a level playing field.
Epic also accused Apple of stopping rivals from launching their own gaming subscription service on its platform.
Apple responded that its rules applied equally to all developers, and that Epic had violated them.
In a statement, the tech giant said Epic's "reckless behavior made pawns of customers, and we look forward to making this clear to the European Commission".
Apple has taken small steps towards changing its practices in recent months.
They now offer lower fees for some developers, and have given them a way to challenge its rulings.
But the changes have done little to satisfy the company's critics.
Big-hitters like Microsoft and Spotify have also criticised the app store's fees and rules.
The European Commission declined to comment on Epic's complaint, but said it was aware of the concerns regarding Apple's App Store rules.