Co-Op Overview

Vanilla Nuclear Throne offers two player local co-op, with up to four players as of update 100. There is a mod for PC versions called Nuclear Throne Together (NTT) that offers 2-4 player co-op with local and online support.

Co-op largely follows the same mechanics as normal mode. Exclusive to this mode is reviving mechanics and unique ultras, which are covered in sections below.

If playing local co-op then at least one player has to use a controller. If the 'gamepad' option under control settings is set to off, then player 1 will use KBM while other players will use controller. If 'gamepad' is set to on, then all players can use controllers. Update 100 allows for multiple controllers to be re-binded in settings.

Using golden weapons or crowns in local co-op: Enter the normal menu first for a singleplayer run and select the desired golden weapons for both characters being played as. For crowns, select the desired starter for whoever Player 1 will select. Whichever is selected will be applied during co-op runs, which also applies to playing as Frog. A run in singleplayer does not need to be started for changes to apply.

Using golden weapons or crowns in NTT co-op: Using /cwep [weapon] changes starting weapon and /ccrown [crown] changes starting crown. (Using /bwep [weapon] changes secondary too if so desired.)

As of update 100, vanilla NT also gives the option of playing hardmode co-op. NTT always has it available using the /hardmode command.

Update 100 also introduces custom which can also be played on co-op. Any loadout settings will apply to all players. Custom is not available on NTT yet as it is not yet u100 compatible.

Run Mechanics

Players on local co-op will have the camera focus between each of the players, meaning they must stick near each other constantly. Only when one player dies is the other given free cam.

What is shared between players:

• Rad meter: Players share leveling up and the rad meter for ultra weapon usage.
• Mutations: Either player can select a mutation on the level up screen, and it counts for both players.
• Crowns: Only one can be run at a time.

What is unique for players:

• Weapons: Each player have their own two weapons. If they wish to trade weapons with each other this can be done with swapping a weapon on the ground.
• HP and Ammo pickups: These will only apply to the player who picked them up, even if they're full. Co-op ultras can cause either to be shared.

Only one player needs to enter the exit portal in order to leave the area. Players cannot friendly fire each other except for projectiles that can also self-damage, such as disc projectiles or explosions.

Bosses gain additional HP for every extra player, following the formula of HP * (1 + (0.5 * (players - 1))). Enemies do not gain any extra health.

This HP modifier is multiplied after loop scaling is accounted for. HP is only rounded at the end of the calculation. Here is an example of co-op health scaling:

Revive Mechanics

Co-op runs only end if all players are fully dead, however if one player dies they can be revived by another. The method of reviving differs by version.

In much older versions of Nuclear Throne, if a player took lethal damage they would fully die for that level, only being revived if an alive player walked over a health chest. This was used up until update 83 when co-op was temporarily disabled, and was swapped out for the fainting mechanic in update 90 on co-op's return. In update 100 it was reverted back to the original method, but instead of health chests, new revive chests were added to the game. (NTT explanation coming soon)

Update 100 Revive Mechanics:

When a player dies they will drop both of their weapons. These can be picked up by alive players, although will not give any additional ammo.

Upon loading any following level the rad canister will be replaced by revive chests, which when walked over (or opened by a portal) it will revive a player with their starting loadout including starting weapons, starting ammo and full health, as if they were starting a new run. Chicken will also return to her max HP.

The chest that spawns will correspond with the character that died:

Revive Chests
Fish	Crystal	Eyes	Melting	Plant	Y.V.	Steroids	Robot
Chicken	Rebel	Horror	Rogue	Cuz	Skeleton	Frog	Big Dog

Revive chests have other niche interactions when spawning, which may not be experienced in a normal run. They are as follows:

• On 7-3 a revive chest will replace the weapon chest. If running Open Mind, it will replace the rad canister instead.
• In Y.V.'s Crib one of the giant weapon chests will be replaced with a revive chest.
• Revive chests will not spawn in Crown Vaults, HQ3 and 0-1.
• If Hostile Horror is eligible to spawn then it still will, even if a revive chest replaces a rad canister.
• A dead player counts as having 0 HP, so if running Open Mind then health chests can still spawn even if the other players are at full health.
• Health chests do not bring other players back to life, unlike its old interaction.
• (Possible Bug) Revived players cannot use Hammerhead in the level they were revived on, only regaining usage in the next level.
• (Possible Bug) Crown of Hatred does not cause damage when opening a revive chest.

Update 99 Revive Mechanics:

If a player dies they'll have a 'FAINTED' sign over them and have a ghost-like appearance. If this ghost sprite is touched by an alive player, they'll gift 50% of their current HP rounded up. Healed players cannot go above their max HP, so for example if base Melting dies only 2 HP would be gifted to bring them to full.
Headless Chicken cannot revive other players. If Chicken faints and is revived she will retain her max HP loss.

A 10 second timer will begin ticking down any time a player is killed. If they are not revived in time, then it will begin to damage alive players at 1 damage a second.

The timer will reset upon entering a new level if one player is still dead. Other forms of gaining HP between levels such as taking Last Wish, taking Rhino Skin or Rebel's passive will not revive dead players. Only walking over them will save them.

If the alive player is only at 1 HP and they try to revive a player, they will then die and swap places. There is a cooldown of 1 second to reviving each other to avoid getting stuck, but otherwise players can chain revive each other to avoid the 10 second counter from running out while they search for health pickups. If at 1 HP with Strong Spirit, this will simply consume Spirit to give 1 HP without killing the player.

Dead players drop their weapons but will automatically be picked back up when revived. The exception to this is if the alive player gets sucked into the exit portal; both will be brought into the next level but the dead player will no longer have their weapons, unless if the weapons happen to get pulled through as well.

Mutation & Passive Mechanics

Coming soon to a Wasteland near you!

Ultra Mutations

Vanilla co-op removes character-specific ultras, giving the option between sharing ammo or health pickups between players.
In NTT there is an option to run character ultras instead through the /ultras command, cannot combine character and co-op ultras.
NTT features (including outlines and ultra mode) can be enabled in vanilla NT by editing the settings file.

Co-Op Ultra Mutations
Blood Bond	"HP Pickups Are Shared" The ultra A co-op option, it makes any health gained apply to both players. This includes health pickups, health chests, Bloodlust and Robot's active. Not included is Rebel's passive. Blood Bond will not cause dead players to be revived, yet can still save Chicken while she is headless.
Gun Bond	"Ammo Pickups Are Shared" The ultra B co-op option, it makes any ammo gained apply to both players. This includes ammo pickups, ammo chests and Robot's active. The player that picks up ammo will have the type chances apply to them, and then that ammo type will also be shared with the other player. Opening an ammo chest will give ammo specific to each players' primary weapons independent of each other. Lucky Shot gives the same ammo type to players, which is randomly chosen.