My daughter (18yrold) just went to a party where they played a "home made" game they called Three Rounds.
Each person was given pieces of paper and wrote down well known slogans, ideas, quotes, etc which are placed in a basket. All players sit in a circle and 2 teams are made up of every other player. A player starts the game by pulling a slip out of the basket and using words to get the others to come up with what's on the slip. Of course, he/she can't say any of the exact words on the paper.
For the second and third rounds the same papers are used and put back in the basket. I forget exactly what the second and third rounds are like, but I think the third round is acting it out like in charades.
She loved this game and said they hadn't had such a good laugh for a long time.
Reply to me if you want more info on this game and I'll ask my daughter to explain it again.
Games from my childhood:
Fruit basket upset - can handle a large crowd.
Charades
Skits or talent show
Musical chairs
Balloon popping hop game - tie a balloon to the ankle and people try to pop other people's balloons
It might be fun to just bring a bunch of card tables and card or board games and let the kids play games. Or import some adults (veterans?) that play dominoes and teach them Mexican train (wreck?) or Chicken Foot or whatever those games are!
Tri-ominoes, Pig Pen, Life, Chance, Parcheesi, Uno, Crazy Eights, Old Maid (paste some of their instructors faces on the cards?), Memory (make your own set of cards using army type pictures or instructors?), Rummy Kub(e?), regular Rummy, Boggle, Pictionary (use large dry erase boards and divide into two large teams)
longer games: Clue, Monopoly, Parcheesi, Chance, Life
Encourage them to switch tables after every game to intermingle.
Or do what my sister-in-law has us do every year after the Thanksgiving meal: we make some kind of craft - one year we made Christmas ornaments out of clay that had to be baked. Amazing creativity!
Have fun!
PS Ask a kindergarten or first grade teacher for inexpensive craft ideas! They're the best! Amazing people!