This is really cool, but I think something needs to be done about getting easier puzzles towards the beginning. Also, the numbers before each puzzle and the collectables (yellow things) are never explained. I've only gotten to play with one puzzle with the sparking and it was bare sufficient to explain what that effect did (only one move I was ever able to make was "bad" because of it).
Roughly speaking:
- 1x1 greens are very difficult to work with
- 1xN greens are tricky if they need to move in their thin-dimension direction
- 1x2 browns are very difficult to work with
- Oddly shaped greens are difficult to work with
- Longer distances to cross are more difficult
- Fewer "excess cells" not needed to form the path are can be difficult to work with
- Oblong greens that are aligned perpendicular to the path direction are frustrating to use (relates to point 2)
In general I feel like I can only get about 10 puzzles deep (not counting the tutorial 3). I have almost no opinion on how yellows effect difficulty, as I've seen very few of them. One was oddly shaped, but the only other piece was a 1x2 brown and it was just a matter of moving the brown around to let the yellow rotate as needed. I guess the 1x2s are the most frustrating that I've seen? Maybe its "how many other pieces are there" that makes them worse to work with?