The Fall Climber is a gorilla/crab-like mecha from the Rebel Army. Designed to climb up cliffs, it is armed with several weapons such as plasma shots and a laser cannon.
The boss battle starts with the mecha climbing up the waterfall and destroying the bridge. The players reside on the mecha's head. There are two POWs on top of each claw who will give the player some weapons.
The Fall Climber fires plasma shots from its back as it climbs up the waterfall. Once its head is popped off, it will also intermittently charge and fire its center laser cannon that will go straight up the waterfall.
Two weapon pods occasionally come out of the fall. The pods fire different weapons depending where it faces:
- Facing Upwards: The pod shoots out red/black bombs that fall down at an arc.
- Facing Forwards: The pods fire missiles that travel around the pillars before homing at the players in the arena. The blue-flashing missiles give the player weapons when shot at.
- Facing Downwards: A laser beam is dragged from one side to the other. One pod fires its laser before the other pod does.
Once it is defeated, the Fall Climber will fire the laser cannon, but instead of killing the player, it will send the player to the entrance of the ruins.
The Fall Climber makes an appearance, this time with the codename "Narutaki" attached to it. It is used by the Rebel Army for desperate situations.
As the original was attached to a waterfall and climbed up and down for navigation, the Fall Mecha was redesigned, with its body flipped over to allow for movement. It uses its iron arms to crush enemies with its mass, delivering a powerful shockwave by overheating its head and making a massive leap. When critically damaged and its fourth skill unlocked, the Fall Mecha continues to fight in a damaged state, its head cover popped off. In this state, its special attack changes from simply crushing enemies with its mass to doing that and following up with a powerful laser attack that devastates anything underneath it.
- The Fall Climber's design and movement is reminiscent of the Seabed Ruins boss from In The Hunt.
- Before its official name reveal in Metal Slug Attack, fans referred the Fall Climber as the "Fall Mecha", the name partially coming from its sprite files in Metal Slug 7/XX.