Hi, we did one last year. Dd 8 and Ds 6. We asked the kids to dress up, got a selection of pirates, princesses and historical costumes.
We gave out HH books instead of favours, you can get the boxes with 20 books in quite cheaply.
I just did normal food but put jelly eyeballs on some of the cup cakes.
If you live anywhere Scotland then the Perth Executioner is amazing. He and his victim do a family torture show, then later he dressed up as a grave digger and told ghost stories. You can find him at horror and history tours in Perth. They are willing to travel a bit for some extra expenses.
Ds also insisted on a dead rat piniata so I made one out of card and tissue paper. I also made an eyeball one as I had 40 kids.
I decorated the hall with medieval party decorations off amazon and used some pirate and princess plates.
We played corners but used HH themes, rotten Roman's ect. Also played a game where I yelled out stuff and they had to do the actions. March for Roman's, row a boat for Vikings, lie on the floor for black death.
I got a couple of toy rats instead of pass the parcel and threw sweets at them.
All in all it was a great party and the kids loved the theme. Good luck.