You can't play Kirby's Epic Yarn yet. Nintendo hasn't finished making it. You can, however, play this: an indie platformer with a very similar - and very cool - mechanic that allows you to reshape the world.
Look at the above screenshot. Our hero is trapped in one diagonal shaft, unable to reach the next on the other side of an impenetrable wall.
Along the walls are nodes. You can link together two nodes and eliminate the part of the level that lies between them. You can see I've linked two nodes, as indicated by that vertical white line.
Our hero can now jump down into the bottom of the next diagonal shaft. I can unlink the two nodes and he'll be able to climb up to the top of that next shaft and continue his way through the level.
It'll make sense once you start playing, trust me.
Fault Line [Nitrome]