I'm not normally one for themed, seasonal gaming... but Halloween seems to lend itself particularly well to playing a particular type of game.
So what are you playing this spooky season?
This year, I'm playing through Castlevania: Dawn of Sorrow (DS version, via the Retroid Pocket 2S). It's not the spookiest entry in the series, but has enough creepy castle exploration to fit the bill.
Night of 100 Frights is pretty well recommended!
There are others, but that's the one that comes to mind first. I think there are some couch co-op ones as well