i love local co-op games! unfirtunately my family arent gamers so i dont really have many people to play with but it was an ok game! one thing i will suggest is you definitely wanna make sure to playtest your game and make sure the controls are easy to share with a partner.
Also, storys cool, musics REALLY cool, maybe consider an intro cutscene / comic panel slideshow to tell the story instead of the text menu? i.e. slideshow example panels: "1 maxi walks into barn, 2. purple portal appears, maxi pulled in, 3. maxi lands fallen on her side in purple dimension, dizzy, hears miro calling from below [end of slideshow/cutscene]"
also, ninja outfits! very cool, consider tying into story, maybe the 2 main characters originally trained as ninjas? how old are they? are they young apprentices? you probably already have some idea but getting that stuff and putting it into cutscenes (also, its especially cool if you can figure out how to say things without using words or like 1 or 2 words, but otherwise ingame dialog is good too)