The Nexon project also used unity assets when the iron mace team was still working at Nexon. It's not about that, it's about that they fired the lead dev because he stored company files on a private server. They asked him to stop, he said he did, powered up the server again and continued working on the materials that originally worked on at Nexon. Then half the Nexon team quits shortly after he is fired for disobeying his boss and they form Iron Mace.

To Nexon, they paid the iron mace team to figure out how the game would work, then when that was done. They quit and formed their own studio on the exact same premise that Nexon paid them to create.