Up Your Arsenal multiplayer

Up Your Arsenal features a competitive multiplayer mode that allows for offline split-screen play with up to four players as well as online play with up to eight players. The multiplayer features ten different maps, most of which are based on locations in the Galactic Rangers' missions in the single-player game, three different game modes, eight weapons, and two vehicles. Multiplayer is primarily team-based, with teams divided into a red and blue team, though certain modes are a free-for-all.

Community
The Insomniac Games website featured a ranked online leaderboard for registered community members, until the servers were shut down on June 6, 2012. The new servers were back up on August 28, 2012 for the PlayStation 3 HD remaster, though no multiplayer was featured for PlayStation Vita. The PS3 servers are set to shut down on February 15, 2018 alongside the Deadlocked multiplayer.

Nodes
Around the map, multiple strategic nodes can be captured by the team to gain ground. This allows the nodes to be used as a spawn point for players of that team, as well as providing weapons and ammo, defensive drones, and in some cases, troopers to defend the nodes or vehicles. Nodes are guarded by troopers and turrets, which will respawn if destroyed after time has passed. Before a node is captured, it is defended by neutral troopers and turrets, which players must destroy to then use the bolt crank.

Nodes are optional in all maps in which Siege can be played. They are always present in Siege mode and are crucial in the Attrition Siege variation. Nodes can also be enabled in Capture the Flag.

Weapons
Ten weapons are available in multiplayer, based on weapons that appear in Up Your Arsenal, as well as Going Commando and Up Your Arsenal. These are the N60 Storm, Blitz Gun, Gravity Bomb, Minirocket Tube, Lava Gun, Flux Rifle, Morph-o-Ray, and the Mine Glove. Players start with the N60 Storm by default, and can obtain other weapons found in crates throughout the map. The possible weapons available for a game can be set in options prior to a match.

The weapons operate similarly to those in single-player mode, though they typically have less ammo. After a weapon has been used to kill three players, it will upgrade to a more powerful version. If a player dies, they will drop all weapons on death.

Vehicles
Two vehicles can be obtained, depending on the map: the Hovership and the Turbo Slider. Both vehicles can be operated by two players: a driver, and one who controls the turret. The Hovership is a slow-moving flying, the driver is able to fly the vehicle freely and fire the twin repeating rocket blasters, while the other player can control a bomb launcher. The Turbo Slider is a fast wheeled vehicle, the driver is able to drive the vehicle and fire a machine gun at the front, while a turret at the back can be controlled by another player.

Gadgets
The Hypershot is enabled by default, and allows the player to swing across various gaps on the map. When enabled, the player can use the Charge Boots to speed around the map.

Siege
In Siege, the primary objective is to destroy the opposing team's base. This is done by destroying the two gatling turrets defending their base, teleporting inside, and destroying the power core. The bases are also guarded by two missile turrets, two troopers, and other map-specific defenses.

Nodes are always present in Siege, and provide a strategic benefit to players in terms of providing spawn points as well as unlocking vehicles, which are often crucial in destroying a base' defenses. One variation of Siege is "Attrition Siege". This variation causes capturing nodes to increase the amount of damage, health, and accuracy of the base defenses and all nodes captured by that team.

Siege is supported on the maps Bakisi Isles, Blackwater City, Hoven Gorge, Korgon Outpost, Metropolis, and Outpost X12.

Capture the Flag
In Capture the Flag, the teams must obtain an opposing team's flag and return it to their own base, to score a point, and a team wins after reaching a score cap, set in options. There are two variations on this mode: in "Normal", the team must also have possession of their own team's flag in addition to the enemy's flag, while in "Chaos", it is only required to retrieve the enemy team's flag to score a point.

All maps support Capture the Flag.

Deathmatch
Deathmatch is a simple mode in which players win by scoring the maximum number of kills, set in options mode. There are two variations on this mode: a simple Deathmatch which is a free-for-all, and Team Deathmatch in which players are divided into teams and must score points for their team. This mode has no nodes or bases, and players will simply respawn at a random point after dying.

All maps support Deathmatch.