Card Mastermind

Wordle asks you to guess a specific 5-letter word with per-letter feedback. Card Connections asks you to group 16 tiles into four themes. Card Mastermind is a deductive attribute puzzle inspired by the classic Mastermind board game — the hidden target is a real sports card from our 9,968-card database, and each guess narrows the answer along four axes: decade, sport, rookie status, and value tier. Green means that attribute is exactly right. Yellow means decade or value tier is one step off. White means wrong. After 10 guesses, you either match all four exactly (a win) or the mystery card is revealed.

Decade and value tier are ordered scales — the 1980s are closer to the 1990s than to the 1920s, and the $100-$999 tier is closer to the $1K-$9.9K tier than to the under-$25 tier. Yellow on these axes gives you actionable signal: you were close, try one step up or down. Sport and rookie status are categorical with no ordering — a card is either baseball or it is not, and either a rookie or not. Those two attributes use binary green-or-white feedback because partial credit would be meaningless.

The S grade is awarded for solving in 2 or fewer guesses. This is possible but very rare — you essentially need to get lucky with your first guess narrowing the answer to a single combination. In Daily mode, the mystery card is seeded from the date, so the answer is the same for every player on a given day. Share your grid emoji pattern to compare with friends. A grade means 3 guesses, B means 4-5, C means 6-7, D means 8-9, F means you ran out of guesses.

Yes. The daily mystery card is selected from the card pool using a deterministic seed based on today's date (plus the first character of your sport filter if you change it). Everyone who plays the same day with the same sport filter gets the same hidden card. Share your emoji grid — 4 squares per guess, green/yellow/white — and compare how many guesses it took to crack it. The card resets each day at local midnight.

The best opening guess maximizes the information you gain regardless of the answer. A neutral opener like "2010s / baseball / rookie / $100-$999" covers high-probability mid-tier ranges in a popular decade and sport. If decade comes back yellow, you know it's either the 2000s or 2020s. If value tier comes back white, you know the card is much cheaper or much more expensive — pivot toward the extremes on your next guess. Each guess should split the remaining possibility space as evenly as possible.

Modern packs emphasize rookies heavily, so rookie-to-veteran ratios skew across decades. In the 1950s-1970s, rookie cards were just cards — most weren't labeled as such. In the 1980s-present, rookies became a recognized category with clear designations like RC stamps, Bowman Chrome 1st, and autographed prospects. If the mystery is from the 1960s, rookie status is harder to predict; if it's from the 2010s-2020s, rookies are the dominant category in our database. Use decade feedback to weight your rookie guess accordingly.