A hidden room? What fun. One of my friends built a hidden room for the long retired but forever remembered iconic Janet Spencer of Boston. If memory serves, they did it with a book case.

Of the 3 play spaces I've built out over the years, the one thing I didn't have was mood lighting. Dimmer switches were a must but, mood lighting would have been cool. Depending on how elaborate you want to get, an integrated sound system with speakers throughout would be cool too. This sounds like such a fun project. I'd love to see photos of it when you are done. Please keep us posted on how it goes. How much square footage do you have to work with? How tall are the ceilings? Is noise a factor?