If you are up to it, make a group competition for speed runs or high scores in a retro title like Mega Man -- and maybe offer a prize to the winner. If you've got a ton of people who aren't that great at or familiar with games, try something more elaborate like a Resident Evil freak-out. The way it works is you turn off all the lights and start up a playthrough of any RE title pre-RE 5 (RE 5 is just too recent to pull off a good scare), or Dead Space. Encourage everyone to be super quiet. Then, when the scares start happening, kick people out of the room whenever they so much as startled at an in-game moment. The licker-through-the-mirrored-glass scene in Resident Evil 2 gets 'em every time.
Idea 3: Drinking games*
Only play these if you want to get drunk and try to follow an actual set of rules created by someone else (to prevent welshing on penalty shots). Anything goes as far as which game you pick, but the important factor is to make a single player experience a group experience. Do not resort to fighting games or the best player will automatically be the least drunk.
*You can adapt these games for non-drinkers by asking them to shotgun a pixie stix package instead of taking a drink -- trust us, they'll feel it like you feel a shot.
Idea 4: Game movies and music
The best parties are more about the people than the entertainment, so ultimately, you may want to keep stuff like games and movies as strictly background noise. Throw on something like Silent Hill, a Resident Evil flick, that awful "video game" movie Frankie Muniz was in, or even the 80s-flavored Mario Bros. film to provide ambiance. Music is a little hard to keep to video game theme, but you can still find or download the Resident Evil or Dead Space soundtracks and play them at a low volume on loop. Just remember not to put drinks on top of the speakers.
However you spend your Halloween, we hope you have a good one. Check out our Gamer's Costume Guide and keep it here for another "Spooky Sunday" feature this time next week.