A very cool game concept in an clever 2D/3D mix which was fun to play :D
Like the bigger the tower, the bigger the fire bullet, is a nice element of it. Or the sound clue so that you hear when they get to close, with an arcade-game like sound.
I also once had two towers in one shadow and i was scared that only one would shot. Its nice that the 'hidden' Tower was still shooting :D
I also enjoyed reading the story. Poor cursed orb of light. The angry eyebrow on the enemies makes them look cute tho :D
My only critic is that the room feels too bright. It doesnt seem like the orb of light is the only source of light. Maybe making the higher parts of the wall darker could create an cool atmosphere. Or in general making it so that its the brightest very close to the orb.
The whole idea already is a cool game with lots of possibilities to expand it. Maybe with the ability to set an option if an hit means instant death or if the player gets more chances. Or maybe im just sad that my unstoppable defense in level 7 wasnt enough xD