Thank you for yout kind words! I'm really glad you liked our game.
To be honest, the whole thing is pretty simple in terms of how it works: we just treated each room as a separate frame of the animation, filling it with tiles and changing color pallete if needed. The submarine serves as an avatar, and it stays on it's place, but everything around it changes when we move to the next room. Took us a lot of hours to animate it all, but judjing by your comment, it was worth it :)