From publisher blurb:
Overlords of Dimension-25 is a role-playing game and setting inspired by the pulp science fiction roleplaying games of the late eighties and early nineties. Those games were, in turn, based upon the novels, comic strips, and movie serial adventures from the 1930s about a man frozen in time for five hundred years.
Dimension-25 is a strange alternate universe in which our solar system more closely resembles the pulp science fiction of the 1930s and 40s.
In this game player characters are refugees from our Earth transported to this strange dimension via a freak accident. There they discover a world ravaged by five hundred years of interplanetary war, a world where fighters from the Earth Resistance struggle to overthrow the oppression of the Martian ARES Consortium. In this strange and alien world the player characters become adventurers and explorers seeking the ancient ruins of the Terran Empire in search of clues that might lead to a way home.