A game I like to play when hosting or attending events is to find and collect a series of buttons. if you collect all 4 or 5 in a series you are entered to win a price. This engages attendees, forces them to connect and network, adds a cost-effective element to the whole event. Here is a small collection of some of the button. Most times focused on the event subject, but sometimes on things like movies, styles, and genres.
Click an image to enlarge.