Remote Controlled Missile (also called the Nikita) is Snake's Side Special Move. The missile can be controlled with the control stick, but Snake is defenseless until the shield button is pressed. Doing so will end the control over the guided missile, causing it to cease its forward movement and drop downwards. The missile will still explode if it hits anything while falling. The missile travels slowly when the control stick is tilted in any direction, but travels quickly in the direction it is facing if the Control Stick is in a neutral position. Strangely, tilting the Control Stick in the direction the missile is facing will also slow it down. The missile has tactical options by setting of traps such as Motion-Sensor Bombs the enemy has placed. It can even serve as a makeshift " traveling shield" because it can stop ranged attacks and projectiles cold by absorbing the damage similar to the Wario Bike. The missile can even be used to trick an opponent by dropping the missile next to a landmine and them both off for a far larger blast radius and damage.
When the missile hits its target, Snake will do a quick fist pump. However, when Snake misses he will quickly droop his head in disappointment. The missile does half its normal damage (around 7%) and has less knockback when dropped. If you turn the missile, it will travel a smaller distance, due to a lack of fuel. The missile functions like an item and can be knocked in the direction the attack would normally knock a character back, however the distance is minimal. This is very bad as Snake is basically forced to drop the missile because even with the slightest knockback, the missile will be facing away the opponent and must turn around to chase after the enemy. The missile will either run out of fuel, the character will run away or advance towards Snake, or will explode when hit with a strong enough attack. The missile is incredibly sturdy and can take around 25% damage before it explodes. It is impossible to destroy the missile with an attack of the enemy's character model and not get hurt from the explosion(e.g. punching, kicking, no weapons).
Origin
Going back to the first Metal Gear game, the RCM was a weapon that Snake had to obtain in order to destroy a target that was otherwise out of reach. Both in the Metal Gear saga and in Brawl, the RCM is one of the few weapons in Snake's arsenal which is almost completely fictional.