So how does that work?
Alright, get this.
We all dressed like Wizards. To the people that were saying they had no wizard cloths, I asked them to just dress like wizards dressing like muggles.(miss matched cloths, ect.)
I bought cheap house rings on Amazon. When everyone arrived, I had them pull a ring from the sorting hat. On the center table, I had 4 glass bowls setup. Each time you completed a beer or a house colored Jello shot(house potion) you put a gem in the corresponding cup.
We had random games, and the winning house would get bonus points awarded to their house. This caused a lot of peer pressure between the houses to really get to drinking.
On top of that, we were playing wizard staff with house colored duct tape. To play wizard staff, you drink a beer. When you get your next beer, you tape it on top of your empty beer to drink. This starts to create a giant staff as the night goes on. Whoever has the largest staff, is the Head Master, and can pretty much order the other wizards around. The longer the staff, the stronger the wizard. After a set time, we awarded the house with the Head Master Bonus points, then counted the points for the house cup.
We still have the bowl of gems and house cup on display on the book case in the living room.
Many people who weren't fans left fans. It is pretty cool because you can still do trivia or beer pong, but just make it a house competition instead of individual.
something else we did was wizard chess with shots. That gets crazy quick.
also...watch out for the Slytherin folks. They tried to cheat by over loading their jar.
If you live near a Hobby Lobby, they have the gems and cups for super cheap. I picked things that kinda fit into the wizarding look, because I planned on displaying them as a memento after the party. All of the friends that attended still talk about the party, and admire the little shrine we have on display.
As far as games, we kept them to a minimal because there were about 20 people, so it was hard to coordinate.
We had wizard duels for wizards that were at least 4th year "4 beers drank and taped into a staff." The way the duel worked was after 4 beers you could challenge another 4th year or higher to a shot gunning contest. Whoever finished first received 2 points for their house. Those beers were not added to the staff, but they still helped your house. You could make the duels worth however much you wanted.
You could combine wizard chess, wizard dueling, trivia and any other drinking game into a wizard tournament of sorts for a set amount of points.
The points would depend on how many people you would have over. My group was kinda wild, and didn't really need any games to loosen them up. They came in, got sorted and instantly started talking trash to the other houses. People wanted to get an early lead, so they started with Jello shots. 1 point per shot or beer.
So with that being said...it was a 21st birthday with a lot of different people coming together to partake in adult drinks. Everyone was very open to just experiencing the night. I didn't let anyone know what to expect beyond we will be wizarding out. It worked out well because no one cried about not getting their "choice" house, or not being in the same house as their friend. I made it clear the sorting hat was the final word in their house assignment. I was paired with a house full of people I had never met, but the common bond of "Ravenclaw" made it about us vs them. My housemates are still my friend now.
never the less...just make sure everyone is safe, and don't let anyone disapparate home drunk.