Look at the image above. See the red circle? Its loop must pass over the red square. It will then have to go around the blue circle.
See the orange circle? It can't form a loop because purple is in the way.
Oh yes, there are wormholes - and that's when things get more interesting.
I did all the 'easy' & 'normal' levels in about 45 minutes. I have not downloaded the paid version.
A more interesting game, that's very similar is Patchmania.
Sang Moon Joo's other games
4 Way Puzzle