Oh man this game is so hard and unforgiving... I mean it's not unfair, when you die it was your fault and 99% of the time you can see it coming on the first try (no trial and error) but esp. the later stages are brutal like old NES games.
However, to make the game less frustrating some (more) levels now have checkpoints.

I've changed the game around a little, you now can and have to collect coins in each level (50%), they are not hidden but sometimes hard to get, to pay someone who lets you advance through the portal at the end of the level to the next stage. It's not only there to provide some replayability and liveliness in each level but as a gameplay device because I can guide the player through the stage that way like in Mario games.
I've added a first version of a hub world too (thanks to JustSid for consulting!) from where you can access each level individually and as often as you like. In the screenshot below you can see the new portal (and thus level end) graphic. Behind each portal there will be a small version of the level or notable elements from the stage as one would expect from a hub world.


(If anyone has a better idea where to put or how to include level information please post it here.)

The main reason for my post/ update: There is only one level left to create (and 1/3rd of a bossfight), then the whole game will be at least completely playable!