Space Crash Simulator

Collide planets built from a million interacting particles.
Space Crash Simulator is a real-time planetary collision sandbox built on GPU-accelerated Smoothed Particle Hydrodynamics — the same class of method used in scientific impact simulation. Every planet, star, and fragment is made of individual particles that attract, compress, melt, and break apart under the forces you set up. Nothing is scripted: fragmentation, shock fronts, tidal stretching, moon formation and accretion all emerge from the equations.
There are no missions and no objectives. You set the initial conditions, press play, and watch what physics does with them.

Scale
Real-time simulation of hundreds of thousands of particles

COMPUTE mode pre-calculates collisions of up to 1,000,000 particles per planet on a modern GPU, streaming to disk for long recordings

Replay with rewind, scrubbing, slow motion and reverse — watch the same impact from any angle, as many times as you want

Gravity solved with a Barnes-Hut octree: every particle pulls on every other one, at scales where summing the pairs directly would be a trillion interactions per step

Build the bodies
Draw your own shapes: sketch a silhouette and extrude or revolve it into a 3D body, with a live preview — then crush it under its own gravity

Spheres, hollow spheres, cubes, walls, discs, rings, sieves, and a lattice space-frame that buckles and shears instead of shattering

Make any body indestructible: unbreakable walls, unstoppable projectiles

Planet textures built in or imported from your own images; procedurally granulated star surfaces

Black holes with accretion discs, gravitational lensing, and tidal disruption

Control the physics
Particle count, mass, viscosity, rest density

Impact velocity, spin, inclination

Impact heating, thermal conduction, radiative cooling

Orbit presets: circular, elliptical, and Roche-limit — one click puts a moon exactly where you want it

Simulation modes
Planetary mode: build a system of planets, moons, walls, black holes and painted shapes, and collide them however you like: head-on impacts, glancing blows, or chaotic multi-body dynamics where tiny differences in setup produce wildly different outcomes

Protoplanetary disc + star: accretion and early system evolution

Galaxy mode: large-scale gravitational interactions between galactic cores (gravity only; SPH does not apply at that scale)

What this is, and isn't
Space Crash Simulator is an open-ended physics tool for people interested in astrophysics, orbital mechanics, impact dynamics, and scientific visualization, or anyone who wants to build a scenario and watch it play out. There is no storyline, no progression system, and no competitive mechanics. The focus is entirely on constructing situations, adjusting parameters, and observing the physical behaviour that follows.