Thanks a lot for the help it started now.
Game wise i have to say it seems pretty nice I really like all the Music and Effect Sound, some things I found weird, were that if you get all 3 Coins to create the portal to the next Level the portal still stays open even tough you died, same "problem" with the coins you collected. I don't know if that was intentional. Besides that very cool idea I really like the double jump and as I already said I think the Soundtracks fits as well and I really enjoy the changing soundtrack for each Level. For an easy improvement I would just add some nicer graphics if that is possible, sadly i don't even know the smallest thing about Construct. But if it is possible to create custom art I would definitely try to add some cool Pixel Art to pimp the Looks, if you don't have Photoshop or something similar what I use for my Pixel Art is https://www.pixilart.com/draw it's very easy and intuitive to use. Good Luck and Well Done Game :P