ldesgoui / balamod

Modloader/Injector/Decompiler that supports ingame code injection for Balatro (linux/windows)

Balamod

Mod loader, Injector and Decompiler that supports in-game code injection for Balatro

Note

Balamod currently works on Windows, and Linux with Proton only.

Summary

• Easy Install
  • Linux
  • Windows
• How to Install Mods
• CLI Usage
  • Example of usages
• Modding
  • Modding API
  • Events
• How to use Code Injection
• How to find the function names, where to inject code, etc...

Easy Install

Linux

Important

Balamod currently works with Proton if you are using Linux.

./balamod -a

Windows

If you're not familiar with command prompt interfaces, place balamod.exe and this file in the same folder, then run the .cmd file.

You can also use the command line:

balamod.exe -a

See How to use Code Injection

How to Install Mods

Just put your mods in the mods folder, and your API in the apis folder on %appdata%/balatro for Windows, or ~/.local/share/Steam/steamapps/compatdata/2379780/pfx/drive_c/users/steamuser/AppData/Roaming/Balatro for Linux.

CLI Usage

Initially, Balamod searches for all Balatro installations.
If a single installation is found, it becomes the default.
For multiple installations, a prompt will allow you to select one.
In case no installation is detected, you will be prompted to specify one using the -b flag.

Example of usages

• Basic Help

  ./balamod --help

• Full Auto-Injection of the Mod Loader

  ./balamod -a

• Injecting a File into the Game

  ./balamod -x -i <file> -o <game_file_name>

• Example to patch an asset file

  ./balamod -x -i balatro.png -o ressources/textures/x4/balatro.png

• Decompiling the game

  ./balamod -d

  or to decompile it into multiple folders,

  ./balamod -d -o MyCustomFolder

If you want to inject game code, you will need to compress it with -c
Example to inject a Lua file:

./balamod -x -c -i Balatro.lua -o DAT1.jkr

Modding

Once the mod loader is in your game, the next time you will launch it, it will create two folders named apis and mods. The apis folder is where you can put your API files, then it will load and inject them into the game before mods. The mods folder is where you can put your mods.

Modding API

Here is an example mod that changes the Planet cards value:

planet_multiplicator_strength = '998'

table.insert(mods,
        {
            mod_id = "planets_multiplicator",
            name = "Planets Multiplicator",
            enabled = true,
            on_enable = function()
                local to_replace = 'amount = amount or 1'
                local replacement = 'amount = ' .. planet_multiplicator_strength
                local fun_name = "level_up_hand"
                local file_name = "functions/common_events.lua"

                inject(file_name, fun_name, to_replace, replacement)
            end,
            on_disable = function()
                local replacement = 'amount = amount or 1'
                local to_replace = 'amount = ' .. planet_multiplicator_strength
                local fun_name = "level_up_hand"
                local file_name = "functions/common_events.lua"

                inject(file_name, fun_name, to_replace, replacement)
            end,
        }
)

For modding, you can edit in-game values on the on enable function and revert them on the on disable function. You can also inject code into the game or remove code from the game with the inject function.

The inject function takes three arguments:

• The function name
• The code to replace (Lua pattern)
• The replacement code (string)

The inject function will replace the first occurence of the pattern in the desired function allowing you to inject code anywhere in the game. If you want to replace code outside a function, you can use classic overring.

Events

Currently (in 0.1.9), the mod loader supports 7 events:

• on_pre_update is called before the game update, if true is returned, it will cancel the update (ticking)
• on_post_update is called after the game update
• on_pre_render is called just before rendering frame functions
• on_post_render is called before rendering the frame itself
• on_key_pressed is called when a key is pressed with the key name
• on_pre_load is called before the game loads
• on_mouse_pressed is called when a mouse button is pressed, with the x and y position, and the button

You can register the events in your mod like this:

-- sendDebugMessage() function is a custom function from dev tools API

table.insert(mods,
        {
            mod_id = "test",
            name = "test",
            enabled = true,
            on_pre_load = function()
            end,
            on_enable = function()
            end,
            on_disable = function()
            end,
            on_pre_update = function()
                sendDebugMessage("pre update")
                return false -- use true to cancel the update
            end,
            on_post_update = function()
                sendDebugMessage("post update")
            end,
            on_pre_render = function()
                sendDebugMessage("pre render") 
                return false -- use true to cancel the rendering
            end,
            on_post_render = function()
                sendDebugMessage("post render")
            end,
            on_key_pressed = function(key_name)
                sendDebugMessage("pressed " .. key_name)
            end,
            on_mouse_pressed = function(x, y, button, touches)
                sendDebugMessage("pressed " .. button .. " at " .. x .. " " .. y)
                return false -- use true to cancel the event
            end
        }
)

These events are not required, you can remove them from your mod if you don't need them.

How to Use Code Injection

Balamod is designed to be lightweight and make minimal changes to the original source code. There is a bundle API that allows you to "hot swap" code while the game is running.

Before the game starts, Balamod will retrieve all the code and store it in a map where one file equals to one key. It allows Balamod to know the current state of the game code, and to overwrite parts of it already loaded by the engine.

To use it, you will need 3 elements:

• The Lua file where you want to inject your code,
• The function name,
• The part of the code you want to replace.

For that, I'll quickly explain with this example that changes the multiplactor of Planet cards.

The inject function takes 4 parameters which are the 3 elements seen above and the new code as 4th parameter. In the mod, it replaces the part that manages the number of cards to be activated very simply like that:

local to_replace = 'amount = amount or 1' -- old code
local replacement = 'amount = ' .. planet_multiplicator_strength -- new code
local fun_name = "level_up_hand"
local file_name = "functions/common_events.lua"

inject(file_name, fun_name, to_replace, replacement)

How to find the function names, where to inject code, etc...

You can use the ./balamod -d command to decompile the game and take a look at the code.

I love Arch, by the way.