Hey Ingix! First of all, thank you for taking the time to comment! It means a lot to us, and we are super glad to hear that you liked the game!
To answer your question, unfortunately I'm afraid not. What you have experienced is the only possible ending. We do feel that a linear story does somewhat hurt replayability, and this is something we put a lot of thought into. Ultimately, we decided that the linearity will not have a huge impact on the players' enjoyment, plus we also wanted to shift focus back onto the puzzles, not the story (not saying the story is not important, but the puzzles should remain the focus in a puzzle game)!
Finally, if you're wondering why the game directory has 33 levels, the reason is the "extra" levels are actually the cut-scenes. :)