Obviously, a well thought-out storyline, with a unique spin on ancient mythology in a modern era. How would have the ancients existed in today's society? How would their tangled relationships have unfolded?
The lead characters, Morgan and Pan, are brilliantly written and equally well played. Ms. Pultro and Mr. Herwick do an excellent job of creating believable humanity and emotion in an other-worldly plot. Hopefully, we'll see more of the secondary characters' story-lines unfold as the series continues.
The complex story is hard to compress into a short web-series episode, and does seem a bit strained at times, but the series does progress nicely. I can only imagine that as the episodes continue, and the strengths of the cast and crew grow, that the "finished product" (by which I mean the entirety of Mythos) will be a stellar example of webertainment.