It is an interesting premise. However for a first interview in an alien environment it may not be fair - but you will probably find the best candidates that can think on their feet - not necessarily those that can think out of the box. In this situation there should probably not be a choice to be left alone. I state this because team players and environments are now the norm. The day of the 'lone gunman' is long past. What better way to see how go a fit will be when 'the chips are down'. I feel that the best use of this type of interview is when one is interviewing a senior applicant for a position no matter whether they are internal or external.