You can play the following games
The Grouping Game This is a good game to play as a mixer. It is a fun, fast moving game. It starts out as everyone collects in one big group. The leader initially calls out a number, usually a number between two and fifteen. The number shouldn't be more than half of the number of total participants. When the number is called out everyone must try to collect in a group that contains that number of people. The group members should be latching arms or have their arms wrapped around each other so that the leader can see who is in the group. If someone cannot enter a group because the number of required members has been reached, he is out of the game. As different numbers are successively called out the number of participants gets smaller and smaller. Eventually, there are less than ten people. The last group, or winning group, should have anywhere from two to five people.
Celebrities
Everyone writes the name of a celebrity, famous person or character on a piece of paper which they stick to the forehead of the player on their left (use tape or office Post-It notes). Make sure they don't see the name.
Everyone else can see your forehead. The objective is to work out who you are.
Going around the table, each payer takes a turn to ask the party questions about who they are - answers can be YES or NO only. If you get a YES you may continue asking, if you get a NO play moves on to the left.
Last person to guess their name is the loser.
Simple, but very absorbing.
Noah's Ark
The group divides in two parallel lines facing each other across the room (perhaps boys/girls but doesn't matter). Each person is assigned an animal whose match is across the room somewhere. After being given a moment of thought, everyone in the room acts like the assigned animal and walks (crawls, flaps, waddles, etc) across the room in search of their mate. No human language is allowed. When people think they have discovered their mate, the go to the referee. The pandemonium proceeds until everyone has been mated.
To help with the assignment of animals perhaps you could make two sets of animal cards to pass out to people. In this case, the people wouldn't need to be in parallel lines across from each other. They could just be in a big circle or anywhere in the room.