Hello,
allthough the games (and their bundle) do not fit into any "spooky" theme, they are part of the Halloween Sale.
http://store.steampowered.com/app/603800/ReThink/
http://store.steampowered.com/app/703500/ReThink__Evolved/
http://store.steampowered.com/bundle/4387/ReThink_Bundle/
Thats all for now.