My 6 year old son's favorite game is Sorry, and this year he decided that was what he wanted to be for Halloween, Sorry Gameboard costume. I purchased 2 pieces of foam board and painted on to look like the gameboard and painted the other to look like the top of the box.
My kids helped me cut pieces of card stock to look like the game cards and we painted them to match. We used yellow and blue clay to make the game pawns and then left them out for a couple of days to harden. We then glued the pawns and cards to the game board.
I put small pieces of foam behind the cards to make it look like a thick deck, when in fact it was only about 5 cards. I connected the boards with a piece of black fabric (with a glue gun) on each side so they would drape over my son's shoulders holding the boards in front and behind him.
I also attached black ribbon on the side of each board so we could tie the boards together at his waist to keep them from flopping when he walked. I made a pawn hat for him out of Styrofoam pieces, ball, cone and round disc, and glued it to an old hat using my glue gun.
It was a very simple costume and my son just loves it. He can't wait for Halloween to wear it.