Check out this illustration before reading - http://i.imgur.com/ySalS.png
I have never played a game like this before in my life. The game goes from being simplistic, to having some hard to grasp puzzle concepts which are still fun once you figure them out, to being completely ♥♥♥♥ing impossible to even someone extremely good at solving puzzles.
The last 3-4 puzzles (including the final puzzle) have no thought put into them for the average player to be able to rationalize any solution out of unless you spend hours looking over the area and just using trial and error over and over.
As for the puzzles just before the end, you can still purchase the solution for 40 orbs, however the final puzzle doesn't grant you access to any help. Even after watching a video of the final puzzle solution I was lost 30 seconds in. If you were trying to play the game at the same time as watching the video, you'll no doubt either ♥♥♥♥ up trying to follow it, or just give up since there's no way the ending is rewarding enough to make up for it. IN CONCLUSION:
This is not a game for the vast majority of players who enjoy puzzle games akin to portal or recent titles like snapshot and closure. The final puzzles are simply too frustating to take the time to solve and nearly ruin the good experience that the rest of the game made for itself. There should at the very least be an option to see the solution to the final puzzle and not leave the player to their wits when trying to solve it.