This simulator places two real catalytic regimes side by side in one 3D scene. On the left, a metal-complex catalyst and its reagents share the same liquid phase, diffusing and reacting through direct coordination at the metal centre. On the right, a crystalline solid catalyst sits in a different phase from the gas-phase reagents above it, and the reaction proceeds through the three real steps of the Langmuir-Hinshelwood mechanism: adsorption onto empty lattice sites, surface diffusion and reaction between neighbouring adsorbed species, and desorption of the product. Switch modes to focus the camera on either regime, start the reaction, and watch turnover counts accumulate on both sides at once.