moonsbox

A sandbox cellular automata playground written in Python with Pygame. Inspired by classic falling sand games, especially SmellyMoo's sand:box, moonsbox lets you experiment with different materials and their interactions in a pixel world.

Features

• Material palette: Choose materials with a visual palette (keyboard/mouse navigation supported)
• Heat simulation: Materials exchange temperature based on heat capacity and thermal conductivity
• Sound effects: Some materials can play sounds on interaction
• Resizable window: The simulation area and camera can be zoomed and panned
• Saving & Screenshot: Share some funny situations with your friends using saves or screenshots
• Highly customizable: Tune your sandbox changing TOML config or assets

Plans

• Move const.py to a config file. (✓)
• Get rid of tkinter.filedialog dependency and make our own opener of native file dialog. (✓)
• Make capturing system for the game on top of FFMPEG. (✓)
• Make the first release of the game. (✓)
• Spread the game. (✓)
• Create a chat for the game. (✓)
• Rewrite high-loaded core of the game in C++ (branch wip-cxx)
• Add more materials
• Add visual configuring
• Create a launcher for the game with visual configuring, managing saves and captures, game updating
• Add touchscreen support
• Add building chain for Android
• Make multiplayer prototype

Controls

• LMB | Ctrl: Draw with the selected material
• RMB | Shift: Move the camera
• Mouse Wheel: Zoom camera
• MMB | Tab: Open the material palette
• Space: Pause simulation
• V: Change render mask (normal/thermal)
• F5: Step simulation
• F6: Clean map
• F10: Take map snapshot
• + | - | Alt + Mouse Wheel: Change brush size
• R: Pause rendering to speed up simulation
• Alt + F12: Begin or end capturing (see Running to convert capture to a video)
• U | Mouse Go Forward: Push current material into material stack
• I | Mouse Go Back: Pop material from the stack (if empty, get Space)
• K: Pick the material of a dot under the mouse cursor

Social

Moonsbox have got its own telegram channel!

If you know Russian and you are interested in the development of moonsbox, please join it.

Requirements

• Python 3 (I run it with Python 3.13.3)
• pygame-ce
• numpy
• toml

Running

# If your platform is not Windows, it's recommended to have tkinter:
python -c "import tkinter" # checks if tkinter is here
# If you don't have one and not using Windows, then if you open file dialogs, you have to enter
# text into console.

# Getting ready
python -m pip install pygame-ce numpy toml
cd <PROJECT DIR>

# Settings are at ./user/config.toml
notepad user\config.toml # if you have Windows
nano user/config.toml # if you have GNU nano

# Running
python -m src

# Converting a capture to a video
# Requires FFMPEG!
ffmpeg -i <CAPTURE DIR>/frame_%06d.png [<further args>]
# Create a video with 60 FPS, x264 codec, scaled to 400x400 (but still pixelated):
ffmpeg -i ./capture_2025-08-05_17-02-33/frame_%06d.png -framerate 60 -vcodec libx264 \
       -sws_flags neighbor -s 400x400 ./testcapt.mp4
rm -rf ./capture_2025-08-05_17-02-33/

License

This project is licensed under the GPL-3.0 License - see the LICENSE file for details.