Coderetreat?
I have shared the first time a coderetreat which was a really amazing thing in particular in seeing how different people going to solve a problem and for myself it was a really a good experience that sometimes the first (obvious) thought about how to solve a problem is not the best way. One thing which was weird to me to delete all written code after every session. But after the first time it helps to get the head clean and start from scratch for the next session. Unfortunately i would like to have taken a look into the different code results of the different sessions afterwards.