This looks really cool, but it needs instructions. I couldn't figure out what any of the buttons do except the one that places turrets. After placing a bunch of turrets they were killing all the enemies before they even appeared onscreen until the very end when I got swarmed by a bunch of grey cubes that seemed to ignore the turrets shooting.

Seemed like an interesting concept. Music was cool. I would like to see more development from this.

Notes:
I never saw any robots spawn to attack me until like the very end where it was probably like a 100 of them that came and a bunch more when the boss spawned.
I wished I could hover over the icons to know what they do. 
I really liked when the timer hit 0 that a boss appeared and the music changed. The boss looked cool, but I wish the rest of the game was in that style because it was 3d and stood out more from the rest of the game.
The map may have been too big and could probably be shortened for a better survival and defending experience while still having sand box elements.

Overall, nice work though!

Needed a little more direction on what things were and how I could and mainly could not place them, liked the concept though nice work <3