It is not easy to understand what to collect on some levels. Additionally, using the area which is not on the screen is not a good idea. I may be misplaying some levels but I could not quite get a solution without shooting off-screen. I think everything should stay in the same frame. I also thougth that the cannon and pinguins are too large for the frame. Again, some objects do not fit into gameplay. Those eskimos for example. They are just obstacles and don't have any gameplay property? (or do they have?) In many levels I started shooting randomly and you eventually collect everything. Yeah I'm aware of the fact that the game is score based but it did not push me to collect items with less shots. Other than these, thew user interface is easy to use and I didn't like the background in the level select screen. The colored thing in front of the cannon does not represent anything so why is that there? if it is here to aim shooting then use a line instead.
I know that making a game is not an easy work but keep working!!