Here's my idea of the setting, tell me if you think it sounds Souls enough to you.
Modern day, apocalyptic. 13 stars fell from the sky, destroying much of Earth. 13 beings emerged from the stars, and began their rule over the blasted land. Their influence has changed the land, making the world look much different from the world of old.
You are a scavenger, abandoned by his group in an effort to save themselves. You fell in a deep crater, and encounter one of the star beings. He calls himself Ophiuchus, the Snake Handler. He gives you a mighty task. Kill the other star creatures, and you will be rewarded by being returned to the world before the stars fell. Refuse, however, and you will be eaten by the snake, and digested for all eternity.
With no other option, you accept, and are given an artifact which makes tools and weapons from stars, collected from the supernatural creatures.
You are cursed, however, with a snake which resurrects you when you die, though you must return to where you were, and collect the stars, or lose them forever. Also, the more you die, the more constructed you become, and the more resources are leeched from you to the snake.
This can only be cured by killing a star being or something legendary, or bribing it with your experience, which proves yourself to the snake, who proceeds to deconstrict itself, letting you have access to resources once again.