I see you changed some things. It's definitely a lot more challenging right now. If you want to make the turrets unmovable, you should make them sellable and buyable though, because a tiny mistake can cause your loss right now. Also I found another issue that pops up since the turrets are unmovable; it's impossible to cancel placing a turret, so if you clicked it, you can't do anything but placing it. Glad to see you are improving the game!