I like how difficult some of the puzzles are. What I don't like so much are some of the ways the puzzles are difficult. One example is the inability to change direction without moving, even though the Life Spark does just that during the "The End(?)" cut scene. What was even more annoying was how the clunkiness of the controls caused me to slip and fall and redo entire puzzles even though I figured out the solution on several occasions. I understand being forced to move one full square every time helps to make most puzzles not have unintended shortcuts, but being able to undo a simple mistake to avoid redoing puzzles you've already solved would have made things a fair amount less frustrating.
As for the story, it's decent, but not very interesting. Maybe if the Life Spark had a personality or had flashbacks when accessing certain archives, the story would become intriguing, especially if we got to see ***SPOILER*** what X (the blue guy) said he saw when the Life Spark tried to possess him. ***END SPOILER***
Overall, it's a good game, but with the following flaws:
-semi-frequent forced restarts due to miss-pressed buttons
-two of the puzzles being unsolvable if you never know the following about the explosive blueprint, which is never explained in-game at all:
1. You don't have to explode every time you use one (though this is rare). On the level you blow up a green spark, you climb on top of an explosive blueprint to get somewhere (if I remember right), just press Space before exploding when in position.
2. Explosive blueprints can explode after leaving them if they drop low enough (wait, what? that doesn't even make sense if the explosive power comes from sparks. How was I supposed to figure that out? I had to find a walkthrough posted in a Kongregate review to find out about that...). You use this in the generator puzzle. Rather than making a stepping stone out of a crate for the explosive blueprint (you use it for the first crate pusher), leave the explosive blueprint on the platform above the cracked wall when the timer says 3, then pull the switch with your second crate pusher to drop the explosive blueprint. From there, proceed to completing the puzzle.
If being able to explode explosive blueprint without being in them was explained somewhere, I'd give this game a 4, but the generator puzzle situation to me is like expecting people to do calculus even though you only taught them algebra. At the bare minimum, adding a "press space here" hint to the generator puzzle would make it more fair.