Great, just great game.
I did not finish it yet, struggling with those numbers and operations (they haunt me) ....
No walk-trough is necessary for this kind of games. It will ruin the game and contribute more to the current trend of easy to play and digest game that are polluting the industry. And please stop giving spoilers.
By the way, I thought I saw the solar system in the keys; curiosity question: was that on purpose?