3 stars for encouragement for further development :-) Two things:
1. The mechanics of jumping: jumping is a bit too fast, this makes it more difficult to reach the subseqent platforms; also sometimes it seems like you are jumping through the platforms;
2. Even more important: the screen should not scroll at the time when you reach the border of the screen but much earlier, because currently you simply can get killed because you see the next enemy... when you step into him. Also sometimes you can't see where are you going to jump next.