Fun, but quite a jump in difficulty!
That game was pretty fun, but that last level took me forever to beat...that mech is way too strong when compared to all the other levels, but I eventually killed him dead! Once you get that rapid 3-shot laser it's all over for him.
The difficulty goes from incredibly easy to about somewhat hard, but after you figure out how to get through the few levels that give you trouble it's overall an easy game...but then there's that mech which tosses the difficulty scale up from about 3 to 10 (from 1-10).
The game was fun, but if you're going to make the game that hard in the end, then you should ease into such a hard boss, not jump from simple to almost impossible.