Meet the Reactions laboratory! • Add acid particles to visibly bonded structures. When two acids attach to the same structure, it breaks into loose fragments and the reacting acids become harmless spent particles. • Change the number of acids needed, attachment strength and fragment recovery time, then restart the same scene to compare results. • Try the seventh guided experiment: Two acids, one structure. Predict, change a rule, observe and explain. • Explore Reactions in 2D and 3D, and save or share complete reaction worlds. Reactions uses invented toy-chemistry rules. Every tool and experiment remains free.