Fortnite's maker just banned hand-written code on its new Star Wars and Marvel game. Sounds crazy until you realize Epic has run this exact play three times since 1998. Unreal shipped in 1998 as a hit game, but the real product was the engine underneath it. Epic licensed that engine out and ended up with a second business bigger than the game. Gears of War did the same job for Unreal Engine 3. Fortnite started as a showcase for UE4, accidentally became the biggest game on earth, and funded…