  Working in complex industrial facilities requires spatial navigation skills
that people build up with time and field experience. Training sessions
consisting in guided tours help discover places but they are insufficient to
become intimately familiar with their layout. They imply passive learning
postures, are time-limited and can be experienced only once because of
organization constraints and potential interferences with ongoing activities in
the buildings. To overcome these limitations and improve the acquisition of
navigation skills, we developed Indy, a virtual reality system consisting in a
collaborative game of treasure hunting. It has several key advantages: it
focuses learners' attention on navigation tasks, implies their active
engagement and provides them with feedbacks on their achievements. Virtual
reality makes it possible to multiply the number and duration of situations
that learners can experience to better consolidate their skills. This paper
discusses the main design principles and a typical usage scenario of Indy.
