This item is only available in French.
Third incarnation of Mega, the "Jeu de rôle des messagers galactiques" allow players to delve in the a trans-dimensional universe where the Guild of the Galactic Messengers travels through space and parallel universes using a tetrahedron structure as a portal.
This is the core rule book that contains everything you need to play.
There are two version of the rules. The hardcover and the special issue version from Casus Belli. The rules content is the same in both (including all the typos). In addition, the hardcover contains erratas, a campaign "Le voleur d'Ygol" as well as more background on the universe.