As these enemies always face towards the player, they must be defeated by throwing a steel barrel[12] over them so it bounces off a wall behind them in order to strike them from behind.[6] The game overworld is also more complex, allowing players to explore between each area instead of forcing them along a linear path. To achieve this, the game includes several vehicles such as a speedboat and hovercraft which can be used to traverse the overworld and access different worlds.[11][13]