Winning teams get small prizes, like a piece of candy. I have used crossword puzzles in several ways. I have divided students into groups and had each group make a crossword using key concepts from the class. This works well as a review for the final. You might be lucky and find a puzzle or you can make one.
Students can then complete it individually or in groups, and then it can be checked.
When I introduce the strategy, I encourage learners to think about the course content as pieces within a kaleidoscope. The kaleidoscope represents the views and beliefs of the learners and, depending on the position of the pieces, aspects of the content can be thought of as transforming and emerging. Before they start, learners are encouraged to do a quick review of the text and their notes. Then they create a collage using only pictures to summarize the content of the class. The collages are taped to the classroom walls.