While you comment and the books recommendation are very interesting, it still doesn’t explain why he had a copyright strike. By whom even ? The copyright infringement notice would certainly explain what he did wrong. I don’t think it’s gameplay related because if gameplay mechanics were copyrightable EA would’ve done that years ago. If it’s story, name related it wouldn’t be the first time someone is forced to change them because copyright. Unless, he provided some more explanations i would think he just got tired of working on the game and wanted an exit.