Create your own solar system with orbital physics
Click to place a Star
Start by placing a star, then add planets around it
Getting Started: Select a celestial body type from the toolbar, then click on the canvas to place it. Start with a Star at the center of your system, then add planets around it.
Orbital Physics: Planets automatically orbit the nearest star. Moons orbit the nearest planet. The further a body is placed from its parent, the wider its orbit and the slower it moves (just like real space!).
Customize Orbits: Click on any orbiting body to select it, then use the sliders to adjust its orbit radius and speed. You can also add or remove rings on planets.
Navigation: Scroll to zoom in/out. Hold Shift + drag (or middle-click drag) to pan the view. On mobile, pinch to zoom and drag with one finger to pan.
Time Controls: Pause the simulation, or speed it up to 2x or 4x to watch your solar system evolve faster.
Scoring: Your score increases based on the complexity of your solar system. More bodies and stable orbits means a higher score!
Body Types: Stars (center of gravity), Rocky Planets, Gas Giants (may have rings!), Ice Planets, Earth-like Planets, Lava Planets, Moons (orbit planets), Asteroids, and Comets (leave glowing trails).
Planet Builder is a creative simulation game where you design and evolve your own planet from a barren rock into a thriving world. Start by choosing your planet's size and composition, then add atmospheres, oceans, landmasses, and eventually life. Each decision affects the planet's habitability score, temperature, and biodiversity. Add volcanic activity for mineral-rich soil, adjust the atmosphere's composition to control temperature, and introduce organisms that form ecosystems. The simulation runs in real time, showing how your choices cascade through interconnected systems. There is no single correct path, as you might build a tropical paradise, an ice world with extremophile life, or a gas giant with floating organisms. The game combines creative expression with light science education, making planetary science concepts tangible and fun to experiment with.