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About Doomsday Simulator
Doomsday Simulator is a planetary-collision sandbox by Benjamin Cooley. Pick an impact scenario, move the camera around Earth, and watch the simulated bodies deform and shed material. It is closer to an experiment than a level-based game: there is no score to chase or fixed ending. This Doomsday Simulator browser build is hosted locally on Solar-Smash.io; it is a separate project, not a mode of the official Solar Smash app.
Start with one clear experiment
In Doomsday Simulator, open the scenario panel and choose Smash Test — Moon → Earth. The view begins around Earth and the Moon approaches. Drag across the scene to orbit the camera; use the mouse wheel to zoom. The time control at the top changes how quickly the event unfolds. If you move past the moment you wanted to study, use Reset Earth and run it again. The Space key pauses or resumes the simulation, while H hides the interface when you want an unobstructed view.
Watch one variable at a time on your first run. Start at the default speed and look for the first contact. Then reset, slow time as the bodies meet, and compare the shape of the debris. Fast-forwarding too early makes the most interesting part easy to miss. The live readouts give you clues about temperature, Earth mass and the Moon's status, but they are model outputs rather than real-world predictions.
Three scenarios worth comparing
Smash Test is the clean baseline: a central Moon–Earth collision. Fastball changes the approach speed, so the resulting excavation and ejecta should look different even though the same two bodies are involved. Moonfall begins with the Moon losing orbital speed; instead of an immediate hit, you can watch a longer fall develop. In Doomsday Simulator, run them in that order and you will see why impact speed and starting orbit matter as much as the size of the object.
After those, try a grazing case such as Hit & Run. Off-centre collisions are less tidy than head-on ones: some material may escape while the bodies keep moving. The sidebar also contains an impactor lab for changing the object and its trajectory yourself. Make a small change, reset, and compare; changing every setting at once makes it hard to tell what caused the result.
Controls and browser requirements
- Drag: rotate the camera around the focused body.
- Mouse wheel: zoom in or out.
- Scenario panel: select a prepared impact.
- Time dial: slow down or accelerate the simulation.
- Space: pause or resume. H: hide or show the interface.
- Reset Earth: restart the current scenario.
This build uses WebGPU and is demanding on the graphics processor. A current browser and capable device are important; older browsers may show a blank or unsupported-player message. This embedded version starts with a lower particle density so it can run on more devices; increasing the particle count may slow or stop it. On a phone, the many small controls and GPU load make desktop play the safer choice. Fullscreen availability depends on the browser; the in-page player is the supported fallback.
How it compares with the games here
If you want quick planet-destruction tools, return to Solar Smash. For building a world before testing disasters, try Fletearth. If the orbital path itself interests you more than the collision, Spaceflight Simulator asks you to design and launch a rocket. The shelf keeps these different approaches together.
Creator and asset credits
Code: Benjamin Cooley, released under the MIT License. Planet and star textures: © Solar System Scope, licensed under CC BY 4.0. The original project and its licence are available on GitHub. Solar-Smash.io is an independent host of this browser build and does not claim to have created the game.