Also, you have the power to crouch and fire off your grappling hook at concrete barriers on the ground to slide across the floor, and grabbing a barrel lets you bring it towards yourself and use it as a weapon and shield. Certain stone walls can be pulled away by using the bionic arm, and enemies can be grabbed and thrown/used as human shields when an upgrade is applied later in the game.

A new mechanic was introduced in Rearmed which was absent from the NES version of the game. In order to hack into enemy computers, you must shoot a ball in different directions hitting blocks, trying to get to the green block. These puzzles get more and more challenging as the game progresses, and start to incorporate such things as teleports. The A button is the shoot button and requires multiple button presses to get multiple shots off.

Another new addition is the ability to gain momentum while suspended. While players got stuck and were forced to drop down in order to shoot their arm to move again in the original title, Rearmed allows the shotgun to propel Spencer backwards to start swinging again.

Weapons

Nathan "Rad" Spencer has a wide variety of weapons in his arsenal, many of which unlock via progressing through the game's many levels. Weapons upgrade when the particular item is found in secret areas or allied bases.

Revolver

The Revolver is a Standard Issue .45 with a nickname of "Daisy." The single-fire pistol is able to shoot three bullets  at a time when upgraded and deals minimal but effective damage.

Grenades

Grenades are thrown, usually over barriers to reach crouched and hiding enemies. Holding down while throwing it drops the grenade to the platform directly beneath Spencer. They are useful for dealing with groups, machines, and unreachable foes.

Plasma Rifle

The Plasma Rifle is a laser weapon that deals very little damage to human enemies, but dishes out lethal force to mechanical beings. It is most effective against patrolling robots and bosses.

Bazooka

A traditional rocket launcher with varying accuracy and enormous power. A single-fire weapon, it kills most standard enemies instantly, and is lethal to the player should they be standing too close to the resulting explosion. The bazooka is upgraded in the final level of the game and allows remote control via the right analog stick (consoles) to maneuver the wayward rocket. Since it deals incredible damage, firing rockets at bosses and groups is very effective.

Shotgun

The 13 gauge "Hagle Breaker" is essential for close combat. While useless at long range, the forceful impact of the spread will kill standard soldiers in a single shot. Shooting the shotgun while suspended from your bionic arm results in momentous propulsion, giving the player a chance to swing again wheras they'd normally have to drop to whatever doom awaited below.

Vector Cannon

This rebounding laser is effective against machines and humans, and is essential for reaching meticulously placed turrets or gunmen. The rebounding shot arcs at a 45 degree angle and shoots up or down depending on the player's standing/crouching stance.

Joe's Machine Gun

This rapid-fire machine gun deals phenomenal damage at a high rate. Essential for quick clean ups and taking down groups, the weapon will push players backwards, if they aren't running while shooting. The weapon initially belonged to Super Joe, and is available upon his rescue.

Body Upgrades

The Helmet, Shin Guards and Bullet Proof Vest

The Helmet, Shin Guards and Bullet Proof Vest all allow players to take an extra hit of damage without it affecting their Hit Points. Once hit with a bullet, the respective piece of armor will degrade and fall off, as indicated by its gold logo flinging off of the character. When one is equipped, one shot is deflected; when two  are equipped, two shots are equipped; when three are equipped, three shots are stopped.

Iron Boots

Unlocking and equipping the Iron Boots means players that swing in to most enemies will plant their metal foot in to their face and likely kill them instantly. Some enemies are not affected by the attack, such as the bulky blue Bomb Expert, Shielded Soldiers and most bosses.

Health Recovery Pills

The pills are actually a liquid that increase your total health.

Power Claw

The Power Claw allows Spencer to grab enemies and throw them, which immediately kills them, or use them as human shields to absorb incoming bullets. Grabbing and throwing an enemy negates any item drops such as health or bonus points.