Halloween is a holiday that isnt what it used to be. Those who remember Halloween night prior to 1985 will remember Halloween as an event that kids totally looked forward to all year. In fact, one could make an argument that Halloween was second only to Christmas as the favorite holiday of the year by most kids. This is made even more impressive by the fact that kids didnt even get a day off! (Okay, Catholic school kids would get November 1st off as that is All Saints Day, but that is besides the point)
Today, Halloween remains popular, but not so much for trick or treating as much as it is for throwing Halloween parties and vegetating in front of the television set watching monster movie marathons on cable TV. (Admittedly, cable TV monster marathons are not as impressive as the old UHF monster marathons as local TV monster mashes were rare, hence, special, but that is also besides the point.)
So, if one is going to move the Halloween festivities indoors, then one needs to make sure that there is a sense of being special that needs to be present. The best way to create this atmosphere is to avoid the Halloween party from being a totally haphazard and random event. In other words, just throwing a specific costume party can end up being a party no different than any other old party other than the fact that some people will be dressed as vampires and werewolves. (And, in some cases, these costumes will actually be an improvement over the way they usually dress the rest of the year.)
Just throwing a party and dubbing it a Halloween party does not make it special. When a party becomes nothing more than a get together of a bunch of people, a party has the unfortunate tendency to slip and fall off into the realm of utter boredom. Now, when the party guests are also saddled with having to play dress up in a series of monster costumes, well, then the party is going to be a disaster.
Perhaps, one such way of making the party less random is to set up a theme. Some guests may only be allowed to dress as werewolves and the other guests may only be allowed to dress as vampires. Then, the evening can consist of a series of games and contests that will pit the two teams against each other. Thats quite a more organized and more fun concept that just sitting around the TV watching horror films. Or worse, watching something on TV that has nothing to do with Halloween!
Also, one needs to pay strict attention to keeping the focus of the party on Halloween by way of using the proper decorations. Orange and black colors, pumpkins, etc. If the decoration of the party are lacking or, heaven forbid, totally unrelated to Halloween, then the party will fall flat by way of proxy. This information should all be a given, but it is shocking how many times people will forget about the simple things that are the major things!
So, keep the party focused on Halloween and avoid randomness without a sense of structure. Do that, and the Halloween party will be increasingly memorable!