Fortnite is ruining my 10yo's summer

I let him play during the school year like 30 mins on weekends but now it's June and he literally wants to play 8 hours a day. Won't go to the park with me, blows off his friends IRL, just stares at his iPad. I set the app limit to 2 hours and he just asks me to override it constantly. It's turning into a battle every single day and I'm losing my mind. How do you guys actually enforce screen time without it becoming WW3 in your house?