It's good, but not original.
Yeah... this game has been made before it's called Robokill.
This is just like a bad version of it.
I still enjoyed this game but not to it's fullest content because I had played Robokill just before playing this game.
I'm going to give you a 7/10 still because I love this style of game and I know you would have put a lot of effort into this game.
Maybe if you enhanced the graphics and made the game-play a bit smoother I would pick this over other games like this.