Translated from the website
"Mega is a French Science-Fiction RPG created in the 80s. Initially published as a special issue of Jeux & Stratégie, it live for 3 revisions ; the last one, Mega III, was published by the magazine Casus Belli in the early 1990s.
Mixing several Sci-Fi genre, as well as fantasy and travel through history or bizarre, Mega "le jeu de rôle des messagers galactiques" sent you into extraordinary adventures."
The rulebook will give you all the rules (system) to play Mega IV, including helpers to convert from the previous edition Mega III.