The one party game I will always recommend is called Broken Picture Telephone.
There are probably other variations of it with different names, but this is the version I've always played.
The rules are a bit hard to follow on paper or in an explanation, but once you're into the game, the rules almost make themselves.
This game is funny and exciting and loosens people up to talk and laugh with one another, and has been a huge hit at all of my parties.
- First, you want to count up how many people are in your group.
- Then give each person some scraps of paper and a pen or pencil.
- They should have as many pieces of paper as there are people in the group.
- Then, each person writes a phrase onto a scrap of paper.
- After the turn is done (when everybody's thought of something and written it down), they pass it to the next person (clockwise or counterclockwise, it makes no difference).
- The more random the phrase, the better (like "off-road velociraptor safari" or something weird like that).
- The next person will have to draw a picture of the phrase on one of their scraps and put that on top of the scrap with the phrase on it.
- The papers get passed to the third person next, and they have to put the picture into words.
- The subjects start to deviate from the original phrase at this point. Play keeps on like this (phrase, picture, phrase) until the scraps are back to their original owners.
Usually, with larger groups, the end results are hilarious.
This game can get fairly dirty, but that depends on the people you play it with.
It's an easy way to get people laughing and comfortable with each other, and it's fun to see how far the subjects deviated from the original phrases.
Adults seem to appreciate Broken Picture Telephone more than children, but it can easily be tailored for either group.