Menhir can be played by two types of rules; the fast rules or the more advanced ones.
The players are korrigan (little elves from Brittany) tribes and they battle each other, year after year, in order to have the biggest field full of menhirs. In order to achieve that goal, you need Menhir seeds, which are given to you by the giant who's guarding the mountain. Afterwards you need magical fertilizer in order to make the seeds grow. But don't forget to make sure they don't steal your seeds!
You can get a free download of this game at:
http://pandocreon.com/jeux/menhir/ (site in english, rules in french)
http://pandocreon.fr/jeux/menhir/ (site in french)
You can also buy its micro-edition version (wood box, real stone pebble as menhir seeds):
http://pandocreon.biz/?l=en (site in english)
http://pandocreon.biz/ (site in french)