An interesting idea, but the fact that the turrets stopped shooting made it not only too difficult for me to even get past the second level, it made it incredibly frustrating. I had no idea you were supposed to destroy the portals until I came to give a rating, maybe that could be made a little clearer.
Visually, it's alright, though the enemies look boring, maybe adding rotation or a different shape for the other type of enemy.
The game is better than many in the jam, but the difficulty and frustration it caused me definitely bump it down in my estimation.