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.
There are a couple of really cool Metroid Zero Mission rom hacks called Metroid Spooky mission and Metroid Spooky Mission 2 which are high quality and fun to play on the GBA.
I also picked up the Resident Evil bundle earlier this year that I should fire up. RE4 is my jam.