In Nomine Satanis/Magna Veritas (often abbreviated as INS/MV) was first designed by the French company Siroz, as of 2003 available in its fourth edition. The French edition of the game was stopped on 2006, with the publication of the sourcebook "On Ferme !" (meaning "We close!"). The game relates the events told in the Bible in a somewhat parodical fashion, and explains the existence of other religions and magic with a sense of humor. The backdrop for the game is the modern world, but one where angels and demons incarnate themselves in human bodies in order to fight for good or evil.
The game is somewhat akin to a superhero game, with player characters having supernatural powers (fueled by power points) and abilities usually far beyond those of a human. A typical adventure includes a lot of enquiry, detective work and roleplay, with a few conflicts during the game, and a big, final one. PCs are supposed to keep secret the existence of supernatural entities, so, in their human guises, have a somewhat "normal" existence. This is often downplayed, however, as many players don't wish to roleplay their character's human guise of (for example) an accountant.
The system is based on a "666-sided" dice, the designers' name for three six-sided dice interpreted as follows: the first and second dice read as the tens and units, are used to determine success or failure, while the third die determines the degree of success. Modifiers are applied to the dice depending on the difficulty of the task at hand. A result of 111 counts as a critical success for angels, while 666 is a critical failures; the results are the opposite for demons.
Each character has an angelic or demonic superior, from which he gains some abilities and a general outlook, and which he can try to summon for help. They are also subject to a hierarchy to which they must write reports about missions, and which controls the characters' improvement.