In the alternative ending of The Matrix Revolutions in The Matrix: Path of Neo the final boss is the MegaSmith. The MegaSmith was used for gameplay reasons, because though the Wachowski Brothers thought the martyr approach suitable for film, they also believed that in an interactive medium such as a video game (based upon the successful completion of goals), this would not work. So, described by the brothers as "A little Hulk versus Galactus action", this character was created to be the more appropriate "final boss" of Path of Neo. The MegaSmith is composed of destroyed buildings, cars, and parts of the road, with the "spectator Smiths" standing around the crater and in the streets acting as the MegaSmith's muscles, resulting in Smith not only becoming the city's people, but the city itself.
After Neo knocks Smith into the crater in the level "Aerial Battle", Smith is sent flying through the ground and up through the street. As Neo relaxes, the surrounding Smiths walk away from the crater. Neo gets out of the crater, and dodges a car which flies through the air and lands in a pile of debris. Neo looks on as Smiths tear up chunks of the road and throw cars into this pile. A truck then speeds into a building and blows it up. Smiths can be seen holding the debris together as it takes on a thirty-story tall humanoid form which is then struck by lightning, powering it up. Neo flies up to watch as the giant humanoid lowers its head onto its shoulders. The giant Smith then pulls a pair of giant Smith Shades from a billboard and puts them on. As an interesting aside, the glasses on the billboard are the same ones Agent Smith wore in the first Matrix film, with the curved nose bar, but when the MegaSmith actually puts them on, they become the ones Agent Smith wears in The Matrix Reloaded and in Revolutions.
After the fight—consisting of Neo dodging blows and building up power to launch more powerful assaults at MegaSmith, damaging one arm and creating a large hole in his chest—Neo flies straight into MegaSmith's mouth, causing the Smiths throughout the Matrix to overload and explode. The player is then shown a short scene from The Matrix: Revolutions of the streets shining with light emanating from the destroyed Smiths.
Read more about this topic: Agent Smith