That looks very interesting! I can't recall having seen a jump'n'run where you build your level. There's the occasional drop a piece of wood etc, but no real building. Will be interesting to see where you go with this. It could open up an infinite world of puzzles if your building material is limited and you have to use it wisely: Are you going to try to make a really difficult jump and save a piece of stone that might come in handy later? Or even use material to gather new ones through the help of NPC's. Would also make for funny rage attacks when you have used all materials, get to the end of the level and realize that you can't make this last jump, but of course you will try anyhow... lol.
Are you using the Tile API for that? Would be great to see a tutorial, I want to start making strategy games where the player can build stuff that NPC will interact with. But that's something for the future, I'm currently building a game where NPC's interact with stuff that was build by the player, but simply by referring to attributes.