One activity I've organized as part of the Amazing Ancestor Race is a puzzle I call Ancestor Match. It should allow the older participants to catch up to the younger ones who will almost certainly get through the first few events quickly.
Then on another piece of paper I listed all the names of those in the photos and threw in two extra, so there are 26 names. It's an easy game - participants are asked to match names to photos.
To make it a bit easier I assigned numbers to each name so those playing only have to write a number under the correct photo.
Because not everyone will know who the ancestors are, I also created pedigree charts with photos and those will be on the wall. The observant family members and friends who spot the charts should realize that there are clues there.
See Part 1 and Part 2 and Part 3 of this series of Genealogy Games for a family reunion.