First, I need to check if "Metartx" is a recognized term in any context. If not, maybe the user meant "MetArt," which is a platform for nude or artistic performances, but that seems unlikely here. Another possibility is that they're referring to a mod or a project in a game that combines metamaterial art (metart) with some other elements. However, combining that with a date and a character name like Polly Flame Princess might be part of a mod or a fan project.