Nicely done
It's fun, and there's a nice atmosphere to it. The art was pretty cool, and fitting, and sort of cute. The music is pretty nostalgic, and gives it a nice retro feel. The intro sequence is really neat. And the voice acting is good in my opinion, compared to a lot of Newgrounds stuff. But by my standards, anything that isn't painful to listen to is good. Seriously though, the voices were great. And I liked the sort of echo effect with the intro narration. The key to good voice acting is to be nice and subtle, and to not assault people's ears.
I certainly have to say the programming was lacking, though. A few bugs include how hard it is to position yourself to file through the bars, dialogue with the cannon guard automatically starting up after finishing but without the window, and reentering rooms from the wrong positions. I could've done better, even with the 3-day time limit.