Mods

Mods are modifications to the base game, ranging from balance changes and additions of content to full rehauls and tools to help other people modify the game. Mods are generally made for Update 19, Update 98, or Nuclear Throne Together (NTT).

Nuclear Throne Together
"Nuclear Throne Together is an experimental mod for Vlambeer's Nuclear Throne, improving the multiplayer-related aspects of the game, adding modding support, and, most notably, adding online multiplayer support for 2-4 players."

Nuclear Throne Together adds mod support for online and offline play. While modders may not have complete, direct access to the source code of the game, they can still complete very complex tasks in terms of modification for the game such as new characters, areas, enemies, weapons, and more. NTT also runs on a modified version of Update 99, so the game content is very current and even includes fixes to bugs that are present in vanilla Update 99.

Other noteworthy features include:
 * Skeleton and Frog are added to the character selection screen and can be played from the start. Skeleton dances in place while frog runs around destroying parts of the terrain.
 * New alternate costumes including a yellow C Skin for Robot, a Hammerhead B Skin for Skeleton, and Yung Cuz as a C Skin for Y.V.
 * The numkeys can be used to place markers where a player's cursor is, allowing them to mark weapons, chests, and other things of interest to other players.
 * Big Dog and Character-specific Ultra Mutations can be reenabled in both Single and Multiplayer using the console.

The Bitbucket and itch.io pages are good sources for finding or uploading NTT mods.

Update 19 Mods
Update 19 mods are made for a much simpler version of the game but they are generally made by altering the source code, giving a wide range of what one can manipulate in the game. Most Update 19 mods can be found on Thronebutt, though some may also be found on itch.io.

Update 98 Mods
Aside from earlier versions of Nuclear Throne Together, there are not many mods for Update 98 that go past modifying in-game sprites, as Update 19 was the last version of the game to run on GameMaker 8.1 which allowed file manipulation. One depository of Update 98 Mods is located here. There is also a seeding tool for Update 98 that can be found here.

Custom Throne
Custom Throne is a "modding toolset that lets you create levels, weapons, characters, enemies, mutations and more, running on a heavily updated u19 engine." It allows for modification of an updated version of Update 19. A depository of Custom Throne mods can be found here.