Metal Saga is set in the same post-apocalyptic world as its predecessors, where bounty hunters, rangers, bandits, and mutant monsters roam free. The player takes on the role of a young man, the son of a famous retired bounty hunter Eddy, living in the town of Junkyard. Refusing to follow a quiet life as a mechanic, he decides to travel the world and hunt down outlaws for rewards.
The game features an open-ended world with non-linear gameplay, allowing players to develop their own story according to their mission choices. The player can ignore the main plot and explore the world map, completing quests for money and fame, which will trigger certain events or character joinings.
Throughout the game, the protagonist can recruit various characters to join his party, including humans and dogs with mounted guns. Enemies appear randomly on the world map and in hostile areas, with combat being turn-based. The player can fight either on foot or in a tank, which must be acquired or rented. Tanks can be customized with different parts, weapons, and accessories, offering hundreds of options.