The only real problem is it needs a pause menu with a help screen. I had to start over because I came back later and had forgotten certain aspects of the game.
If you really want to make it easy at first, keep playing level 3 over and over again. Every time it gives you an upgrade point and a good amount of money.
This game was ruined for me by the fact there is no difficulty gradient. Its really easy until you get to the third area and then BAM!!, freaking impossible.