I wasn't sure where to put this, I found it while wandering around an OSM site.
Mel Birkrant's Invasion Earth
It looks really cool and has a lot of what I like in a line. A wide variety of characters, fairly uniform army type style, neat vehicles (most passenger friendly), a token girl, etc...
If OSM is to slow down or die off, this would be a neat property for the 4H to explore.