Hi-Lo

One 52-card deck, freshly shuffled every round with a crypto Fisher-Yates shuffle. Guess whether the next card ranks higher or lower than the one showing — a tie counts as a loss for both directions. Rank order is A (low) through K (high).

Because it is a real deck with no replacement, the exact count of cards left that would win each guess is known precisely at every step, and the multiplier offered is 0.99 / P(that guess wins), recomputed fresh each time from what has actually been dealt. A direction with zero winning cards left is disabled rather than offered at odds that can't pay.

RTP is exactly 99.00% on every correct guess — see `npm run rtp`.