LÖVE

The first three levels looks very polished and juicy , but I cant jump onto the first platform on level 3

Are you using a variable timestep? If so, I guess my 30 fps are the problem. As you can see in this article the maximal jump height decreseases with fps when using a variable timestep. This makes your game unplayeable on some computers. If that not the problem, the article might be an interesting read anyway.

I once tried to implement the bugfix which is also mentionend in the article, but for simple games like this most often a fixed timestep is more appropriate.

Thanks for the feedback.. I think I fixed the time step using I also released a bit more add-on to it since last release

Sorry I only have an old netbook. I had to disable loading the light and postshader modules, because my computer doesn't support shaders, but then i was able to play all levels! Maybe you want to make shaders optional?

I also tried lowering the window size to 640*480. This worked remarkeable well, only the camera does not follow the character into the edges of the map. I checked that you use values relative to window.getWidth, so i confused why the camera does not work independent of window size.

I really like the art style of the parallax background!

The game seems to be ok in programming, audio and graphics, so maybe you should now concentrate on level design? Here are Ten Principles of Good Level Design. But maybe those are not really applicable to your game. I wonder if there are any other interesting articles about level design.

here is some level critic:
2 & 7) broke the 4th wall? its just strange if you hit your head on an invisible wall/the screen top.
3) The jump to the big pile of rubies in the middle in lvl 3 is a bit hard, which stands in contrast to the generell friendly feeling that graphics and sound create.