***Mild spoilerage for a half-hour game, play it before reading as this comment is meant for the developers***
I loved the art and concepts. I think you have a great foundation, but I would build it out a little more. Specificaly, the puzzles were too easy and I felt like I was playing a tutorial the entire time (which may have been your intention). you could have used ecactly the same mechanics and recombined them to make a much more challenging experience.
Also, I played through twice to make the oposite choices I made the first time. I loved the story and got a"Shadow of the Colosus" vibe from the hero making bad choices to save their loved one. That said, I think Yama was to similar to the Atma ending.
the first time I reached Atma/Yama, I did have a game breaking situation where the smaller floating heads would stop moving after I had destroyed 3/4 of them, and the fourth would just hang just outside of my Mantra box where I could not finish him. I think the last attack I landed on him pushed him out of the normal zone, but I am not sure. This happened on both of my play-throughs.
I sound pretty negative, but I genuinly think this could be expanded into a paid product, maybe with a couple new enemies and puzzles. If you're done with this project, please start on a new one as I can tell you are incredible and can't wait to see what else you do!!!