SpaceSim is a scientifically oriented software for modeling astrophysical processes, built around particles, gravity, and hydrodynamics. The project allows not only to observe cosmic phenomena but to recreate them with a high degree of physical fidelity, exploring how massive bodies, fluids, and fields interact under extreme conditions. It is a tool for studying, experimenting with, and visually analyzing complex scenarios. Space as an experiment Users can reproduce real-life events described in scientific literature, including the formation of the Moon, the formation of planetary rings, or asteroid collisions. They can also set their own initial conditions and observe how events unfold. Planetary collisions, unstable orbits, and exotic matter types become available for unlimited exploration. The simulation is based on particle interactions via gravity and the Navier-Stokes equations. Objects can be either deformable or rigid, providing flexibility between accuracy and performance. The result is a clear and dynamic representation of processes typically hidden behind formulas and graphs. Features of the program Particle-based modeling of astrophysical processes. Gravity and hydrodynamics with physical accuracy. Support for real and hypothetical scenarios. Visualization of complex space collisions and systems.