I haven't seen anyone mention this yet, so I felt the need to say it myself. Holy crap are the transitions in this game done well! There's normally a good chance that I just disable or edit overly fancy, 'artsy' or drawn out transitions in renpy games, especially if it feels like they're just getting in the way of the story or wasting my time. The ones in Mythos fit really well with the tone of the game, have a good variety of styles, and aren't over used. If you ever wonder if people notice or if they're worth the effort, at least one person's noticed and thinks they are.
I'm enjoying the rest of the game too btw, but I really noticed the effort put into to the transitions and felt they needed a mention. Weird thing to gush about I guess, but there you go.