meh...
There's many things that are off with this game. One thing that I noticed is if you spend money, then don't save and start the next level and fail (which happens so often) the money you spent is gone and the upgrade you bought is no more. So essentially you wasted x amount of money which is so difficult to come buy since you don't make many money from failing a level. I would have gone through the game a few more times to fix little things like this which makes the game so hard to play. I could probably do better but I'm playing on a mousepad.