Under rating threshold (hideshow)
I almost wish that there were a few more puzzles, such that you'd find Mur's note earlier, but not be able to escape until a later puzzle.
Also my most favorite of the Submachines, only needed a hint on 3 and 7, though I should have been able to figure 3 out on my own had I poked a few more buttons. 7 I just felt stupid when I read the solution.
Here's to hoping for a #5. :)