14:28 for me.
Was a nice game just way too short for my taste :-)
Expand the game a bit, make some of the movable rooms only usable once you got certain powerups. (I mean for example that the room has some death pit in iit that can only be overcome by having some hover ability. if you don't have that you cant cross that room and therefor placing it would be useless)
and hiding these abilities in the fixed location rooms.
probably build some other fixed room with some miniboss in front of it.