This simulator renders the SN1 (unimolecular nucleophilic substitution) mechanism as a real 3D molecule: a chiral carbon bonded to a leaving group and three distinct substituents ionizes into a flat, sp²-hybridized carbocation, then a nucleophile bonds to either face of that planar intermediate. Attack on the front face restores the original configuration (retention); attack on the back face flips it (inversion) — exactly like the Walden inversion of SN2, but here either outcome is possible because the leaving group has already fully departed before the nucleophile arrives. Choose a substrate stability class, tune solvent ionizing power and how tightly the ion pair stays associated, then run single trials or batches of fifty to watch the retention/inversion statistics converge — with a built-in inversion excess when the ion pair stays tight, exactly as measured in real solvolysis experiments.