I've played this alone and with several different groups. Using the solo mode as a 'play as prep' kind of solitaire, I've created Cindercrest Castle, with a rich and rather sad history.  With the groups I've played, we've created some really interesting designs that would make the mad king Ludwig blush. 

I can't recommend this enough as a tool in a GM's kit or as a playful stand-in for those days where half your players can't show.