Prisme · blind Arena

Blind Bitcoin prediction game: your chart reading scored with the Brier score

The Prisme Arena is a free game, with no account, to test how you read a Bitcoin chart blind. A 48-hour window drawn from the Binance BTCUSDT archive since 2017 is shown without dates, rebased to 100. You call up or not up with a confidence from 50 to 99%; your answer is frozen, then scored with the Brier score.

How a round is played

• 192 fifteen-minute candles, prices rebased to 100, dates hidden: the outcome stays on the server until the reveal.
• Horizons of 4 h, 24 h or 7 days; “up” or “not up”, confidence from 50 to 99%, answer frozen before the reveal.
• Tools during the round, on the visible past only: 15 min, 1 h, 4 h, log scale, six indicators, levels, trend lines, zones, measurements.
• Summary per horizon: mean Brier, 50% baseline (0.250) and a baseline taken from the visible past.
• A score card is published only if you create it; no ranking and no claim of skill.

How the Brier score is computed

Brier = (probability of a rise − outcome)², with outcome 1 for a rise and 0 otherwise; an unchanged close counts as “not up”. The smaller the score, the better. Calling a 70% chance of a rise gives 0.09 if it happens, 0.49 otherwise; always answering 50% gives 0.250. Rounds overlap: they are exercises, not independent observations.

Data: frozen Binance BTCUSDT 15-minute archive, since August 2017. Bitcoin only. An anonymous session keeps your rounds; nobody else’s forecasts are ever served. Exploration, not a verdict.