A nice and easily realizable feature would be having subgroups in groups, so that a family can have siblings in one subgroup and parents in another. Or in a company the different teams (developers, management etc.) can compete with each other whilst still sharing the same main group. This would also allow for a more fairly distributed chances, such as if there are multiple kids in one group and the grown ups each alone. One way to realize this would be thru tags. Such that members of a group can be given the tag "x" and others "y" and or "z" wherein the tags assort them to subgroups.