Just Cause 3 is a third-person, open-world action-adventure game set on the fictional Mediterranean island nation of Medici. Players explore a large open environment spanning several biomes, using a grappling hook, parachute, and wingsuit to move quickly across land, sea, and air. Gameplay centers on physics-driven destruction and player freedom, with a wide range of weapons, vehicles, and explosives used to dismantle enemy installations and liberate towns and bases. It is the third entry in the Just Cause series and was followed by Just Cause 4.

Set six years after the events of Just Cause 2, the story follows mercenary Rico Rodriguez as he returns to Medici, his fictional Mediterranean homeland, which has fallen under the rule of the dictator General Sebastiano Di Ravello. Hoping to free his people, Rico joins an underground resistance movement led by his oldest friend, Mario Frigo, and reconnects with allies from his past. As the rebellion struggles to hold together, Rico learns that Di Ravello is mining a rare and powerful mineral found only on the island, intending to use it to build an unmatched arsenal. Rico sets out to weaken the regime and support the fight to reclaim Medici.