its not very easy to play, there are no intructions

I think your premise is interesting, but the way it is developed it's quite unplayable... here are some tips:

- Add a starting screen with some instructions on how to play (that's vital - the info you wrote are quite cryptic)
- The screen scrolls down when the cursor hovers over the three (turrets?) at the lower left

That said, I truly wasn't able to build a single turret, as clicking on them does nothing... am I doing something wrong, am I missing something? Again, there's why instructions are vital. I'll gladly revisit my review as soon as I know how to play the game :)