Is it a 300 prequel, sequel, or set concurrently with the events of 300? Yes. It somehow manages to be all of the above, and manages to come up with a story that leads up to the events of the original and sorta what happens afterwards as well as creating a storyline of what was happening at the same time somewhere else. It's also always fun when original actors return in cameos to reprise their roles to give further character backstory especially the "this is madness!" guy who manages to get a quick story arc.