The carnival theme is always a favorite weird vibe for Halloween. With some cardboard, colored lights, and clown elements, one could do a fantastic job decorating with the carnival theme -
Sideshow posters and jars with strange creatures in them, clowns, carnival music, and bright lights are great components.
Carnival music HERE
This display in a window would be amazing - I'd use styrofoam heads with plaster of paris coating and then painted, utilizing cardboard boxes for the game body or carved styrofoam.
Remember, carnivals are colorful streamers, tents, games of skill, music, lights, clowns, fortunetellers, sideshow freaks.