Check out the rules:
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1. You cannot submit a game that you have been working on before the game jam’s start date.  Eligible games will have only been developed during the game jam’s duration.
   1. However, it is fine if you want to set up an empty project and integrate Backtrace before the jam officially kicks off (~24 hours in advance).  We actually highly recommend that all participants do this so they can focus more on their game during the jam!

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Basically, yeah it is fine to set it up ahead of time.  We just want to make sure people arent actually building out their game.  If you start the game jam with an empty project + Backtrace integrated + some packages installed, that is fine.