Thank you for your remarks. Some of them I acknowledge and I want to address them in future releases or sequels. It's true that the latter parts of the game are more about solving puzzles and a lot less about interesting landscapes. Putting "companion" cubes on push plates may remind Portal a bit too much. I wanted the player to know immediately what he must do. But puzzles themselves are not at all the same than Portal (mechanics, solutions, ...). I hope that each of the 4 main puzzles can produce an epiphany for the player.
I do agree that exploring outside the main path is not very possible, and that you can get stuck in several puzzle, and being forced to reset. I didn't find simple solutions to avoid the player getting stuck, or loosing himself, or avoiding solving the puzzles. In the sequels, I will try to add more exploration level like the first room. I will also try to design puzzles with no fail state.