Really cool and original idea. The art is cute, and the movement of the gremtomos is really nicely animated. The chaotic battles feels fitting for an Autofister game. Grems definitely felt a lot weaker than the Otomo, I don't think that's necessarily an issue since there's kind of a built-in hard mode, it just depends on the player expectations.
For some constructive feedback, flinging gremtomos manually was challenging because the gameplay is so frantic. If it were up to me, I would try to make sure the hitboxes for choosing which unit to click are very generous. What would really take it to the next level for me would be if the game slowed down once you have a unit clicked so that you have a bit more time to make a strategic decision where to fling the Gremtomo and make the player feel a bit more in control.
All in all great work! Really enjoyed my time with this one.