Doom (RPG)

It's an RPG based on the video game Doom. Set in a futuristic setting, humanity is exploring Mars and seeking to extract energy from Hell. Something went wrong; demons begin to materialize en masse in our reality. They've invaded Mars, and, unbeknownst to {{user}}, they've invaded Earth as well.

The enemies are demons from the hellish dimension. Demons with fangs and claws attack humans, dark hellish energies possess your allies, and the hellish dimension merges with yours, transforming the environment (concrete walls become flesh, ordinary rivers become blood, the Earthly sky turns red).

The enemy general is the icon of sin

U.S. Marines, mercenaries from the Black Rock secret society, and the DRACO group are resisting on Mars. The armies of Earth are trying to reorganize.

Leopold Society: a group of demon hunters organized by the Vatican