FIMS Overhaul for Humankind is a free mod designed to enrich gameplay by rebalancing various mechanics in the game. It introduces significant changes to the management of pops, city caps, and resource production, offering a more intricate and strategic experience. Key features include a modified Empire Sprawl system that penalizes players for exceeding administrative caps, and the introduction of a new strategic resource, Military Supplies, which impacts unit upkeep costs. Additionally, the mod alters pollution penalties and introduces stability penalties based on religion and territorial influence.

The gameplay adjustments extend to production mechanics, with changes in how pops contribute to resource generation based on district exploitation. Many bonuses have shifted from flat rates to percentages, enhancing the overall complexity of city management. Other adjustments include rebalanced cultures, modified tech costs, and an increase in fame rewards for controlling wonders. Overall, this mod aims to create a more engaging and challenging environment for players looking to deepen their strategic gameplay in Humankind.