Our large group game format is designed to support large parties, generally between 15-150 guests. It is difficult to conduct a murder mystery game for parties larger than 150 because you lose the interaction between the cast and guests detectives.

Here are a few suggestions if you have a really large event:

1. Conduct the murder mystery so it is played in parallel in multiple rooms.  This is best if you have separate casts for each room, but can be accommodated with a single cast if you time things right.
2. Conduct the murder mystery more like a play with a stage and microphones.  This is less interactive and can be boring if you are not careful.

Go here to learn How to Host a Large Group Team Building Game. Go here to learn what is different about the Team Building version.