The Pre-Abandonment era was a thriving era of exploration, magic, science, and technology. There were nearly 200 different countries throughout the world between the Ranabiri and Watamutum. Towards the end of the era, issues regarding the increase in Priss Events caused an increase in hostilities between developed nations and wars over natural resources needed in magical technology caused the creation of weapons of mass destruction in the form of the giant lifeforms, like The Thirteen Almighty Primal Lords.
From a role-play standpoint, any system supporting a fantasy steampunk setting can be used. Games about exploring new cultures, old ruins, and political intrigue are great for this era and their are plenty of systems out there to accommodate you campaign. Check out some of these:
The Abandonment is the roughly 30-50 years after the God Primal
awoke and began its war against the Homon. There were still some technologies capable of working and knowledge loss is minimal as people are still largely literate and languages having had time to evolve to the point of being unrecognizable. Rumors and misinformation spread easily, as people scramble to find a way to end the reign of the giants beasts destroying their way of life. Tribal factions are already forming and people now compete for resources once plentiful and accessible with relative ease, such as food and water. The plants and animals have begun to mutate and evolve under the influence of the God Primal.
Gritty campaigns about outlasting the horrors of the end of the world are a good fit here and your table could even lay the foundations for the tribe of the future! Consider using a fantasy steampunk setting like mentioned above then pull in elements from some survival RPGs like:
The truth about history is completely obscured by the loss of literacy and the linguistic shifts that have been made as people come together in tribes only to be scattered against by the hostile world of beasts and giants. All hope is not lost however as your table is meant to work over generations to carve out a niche for their tribe that protects them from the worst the world has to offer!
This the era the DAMP TTRPG system was designed for. Players will be creating not only individuals but a historical legacy.