Good for a rainy or lazy afternoon activity OR as a team party challenge.
For a party game, divide your group into small enough teams that they can actually work together, say 2 or 3 kids per team, and set them all up with an equal number of plastic cups. Challenge them to build the tallest, skinniest, most complex, most whatever that matches their age and ability levels.
They do need a level base, like a hardwood floor, or table, to build on. Two teams, one either side of a table, will work just fine. Give them only so many minutes, say 5 or 7, so the pressure is on to get the job done.