Every trader in this pit knows exactly one number: their own. A buyer knows the most they'd pay; a seller knows the least they'd take. Nobody sees the supply or demand curve, and nobody computes the market price.
Yet when a random buyer and seller meet and the buyer's max clears the seller's min, they split the difference and a trade prints. The best-matched pairs deal first and step aside, so the traders still shouting have numbers ever closer together — and the tape narrows onto the one price where quantity demanded equals quantity supplied. That is equilibrium, and it emerged from self-interest alone. Adam Smith's invisible hand.
Clamp a price ceiling below that point and the hand is handcuffed: high-cost sellers walk off, willing buyers with cash pile onto the rail, and you can count the shortage. A cap doesn't lower demand — it just turns it into a line. The shaded wedge is the deadweight loss: trades that should have happened and now can't.
Raise buyer incomes and the whole demand ladder lifts; the tape drifts to a new, higher home and re-solves in seconds. Shift a curve, shift the equilibrium.
Something in the simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.