I'm not sure what ideas have already been used but here's a few.
1) Greek Gods & Goddesses - can even go with egyptian, norse, aztec, mayan and so on
2) not to sure what to call it but dress up as fictional or non-fictional characters who are deadly like
freddy kruger, hannibal lector, jack the ripper, dexter mogan...
3) Guards & Prisoners - this can be AP
That's all I got for now.
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