Call the Grand Exchange

Each day one well-known Old School RuneScape item is featured — gear people save for, or supplies people buy by the thousand. You call whether it will finish up or down. Voting closes at 00:00 UTC, the starting price is taken at that moment, and the round settles 24 hours later against the closing price.

The order matters. Because the starting price is taken after the last call is cast, there is nothing to look up while you are deciding — the answer does not exist yet. That is the whole reason the live chart can stay on screen next to the buttons instead of being hidden from you.

Once you have called today's round you can back an item for a future one, and the most-backed item runs. Only items that are actually being traded are eligible, so a search will turn up an abyssal whip and not an obscure one-off. Anything priced in small change is excluded — a single gp on a four-gp rune is a twelve percent move, which makes for a poor round — and so is anything that has sat perfectly still all day, since a round that does not move is a round that counts for nobody. On a quiet day with no backers, the featured item comes from a curated list instead.

Signed-in players get 10,000,000 coins at the start of each week and can put some of them behind a call. Both sides are priced on screen from the first call, so you can see what each one pays before you take it. The pot grows until calls close, and you can keep adding to yours until the fifth call lands — after that a call already made is fixed, so the price you took is the one you keep. Everyone who called it right splits the pot in proportion to what they committed, so the popular call pays a little and the unpopular one pays a lot — nobody sets the odds, the crowd does. If nobody takes the other side at all, the house takes it and matches the pot coin for coin, so a call with no one against it pays about 2× when it lands and costs the stake when it misses. That is the one place coins are ever created, and it is out of reach of anyone holding both sides, because holding both sides is exactly what keeps the house out of the round. The pot keeps 2% either way, the same cut the Grand Exchange takes on a sale.

Every Monday the coins reset and everyone starts level again, which is what keeps a week winnable by anyone rather than settled by whoever got ahead first. A place on the leaderboard takes 4 settled rounds, so one lucky call does not top it and a bad week does not end you. What does not reset is your career, and it moves on every round rather than once a week: a right call is worth 6 points and a wrong one costs 3, banked the moment the round settles, coins on it or not. A season that ends with more right calls than wrong pays a bonus on top — 5 more for every correct call, doubled for a season with nothing wrong on it, and a placement award if you also finished near the top of the coin ladder. Call a season wrong more often than right and you keep what your good rounds earned and collect nothing further. A total never falls below zero, and it builds a permanent rank from Bronze up to Dragon. Coins are play money. They are never bought, never sold, and never move between players.

How much you commit is worth something beyond the round itself. Finish a week holding 4× what you started with and the season pays 80 points of career on top, 2× what you started with and the season pays 40 points of career on top — the one award on the ladder earned by how much you risked rather than by how well you called, and the only one a week spent committing the minimum cannot reach. The two biggest single calls of the week are named under the leaderboard as well: the largest multiplier anyone took, and the largest stake that came off. They are rarely the same person, because a big stake is a bigger share of the winning side and so takes a smaller multiple of itself.