for the next 60 seconds, you are the matching engine of a stock exchange.
orders arrive. if an order crosses the book, click the resting order it must fill first: best price wins, and at the same price, whoever queued first. if nothing crosses, book it.
when your shift ends, the real engine replays your exact order flow. it will not take 60 seconds.
price-time priority · one seeded market · same orders for everyone