I really enjoyed playing this! Got really into the flow state, very impressive how you managed to evoke that. Kind of fits the 'narrative' of the game as well, the meditative state the player character is in. On the other hand, playing the game is kind of stressful too, so there's some thematic friction there, too. Not that that hinders the experience in any way, of course.
The main mechanic is enjoyable, I feel like you managed to find a good sweetspot of when a drawn shape registers and when it doesn't. The circle is maybe one exception, but I was playing with mouse, so I'm not sure I can really put that out there as criticism.
The game matches the theme okay, I would say: I missed three characters, but don't feel like it's unreasonable to not miss any of them. What I mean is: I don't feel like I was forced to make a tough decision, I just didn't get around to saving some of them.
One other thing I'd like to put out there as 'criticism' (though I really liked the game!) is that the combo system could, maybe in a more developed version of this game, be given more importance. In my experience, the most optimal way to play was to just be very quick with drawing the shapes, not necessarily looking out for combo's. Maybe, if players engage a certain soul by drawing their first symbol, they're 'locked' to that soul and have to finish it. That would heighten the importance of thinking ahead, which isn't really required right now. Just an idea!