I had fuuuun :D Ripping through the building and trying to connect all the rooms was fun. The car controlled well enough to be fun, but badly enough to make it a bit unpredictable- drifting through the walls (and dudes), and suddenly destroying a load bearing wall just felt NICE!
Graphics and music felt like a game from a CD-ROM called "300 best games", that you'd buy in 1996! I dig it :)
As for the use of the theme... I didn't feel I was making a "one room". It felt more like connecting many rooms. Worse- at the start I thought I needed to destroy all the walls to make the room one, and I was surprised, when the level finished (and I got an A rank!)
Over all- really fun game, but a deeper exploration of the theme would be nice.