What I liked:
- the 3d models and their animations (I really like 3d models in a 2D game)
- the background
- that you have to defend something
- the game play loop
- how polished the game felt
What I didn't like:
- the controls (they were the hardest thing) -> fix: offer different controls schemes
- that you get lost and don't know where "the drone" is -> fix: add some kind of arrow that guides you in the direction if you are too far away
- repetitive audio -> fix: add different versions of the same sound and then randomly select of them.