Overview

Cat in the Box is a quantum trick-taking card game inspired by Schrodinger’s Cat. Cards in your hand have numbers but no suits — you declare the suit when you play them. A shared board tracks which number-suit combinations have been claimed. You cannot declare a combination already taken, and if you cannot legally play, you cause a paradox and score negative points. The game rewards winning tricks, especially consecutive ones, while avoiding paradoxes.

Components

• 45 number cards (values 1-5, no suit printed)
• 1 research board (grid: 4 suits x 5 numbers)
• Player tokens (to mark claimed number-suit combos)
• Score track
• Trump indicator
• Round cards

Setup

1. Place the research board in the center.
2. Each player takes a set of player tokens.
3. Deal cards equally to each player (hand size depends on player count). Each player also places one card face-down as a prediction card.
4. Clear the research board at the start of each round.

Turn Structure

The game is played over multiple rounds of trick-taking.

Leading a trick: The lead player plays a card from their hand, declares its number AND suit, and places their token on the corresponding space of the research board.

Following a trick: Each subsequent player plays a card and declares its suit. If the lead suit has been played, you must follow suit if you can (i.e., you must declare the lead suit if at least one number in that suit is still available on the board for you). If you cannot follow suit, declare any other suit.

Winning a trick: The highest card of the lead suit wins, unless a trump card was played, in which case the highest trump wins. The winner leads the next trick.

Actions

Each card play requires two decisions:

1. Which card to play (choose a number from your hand).
2. What suit to declare (place your token on the matching grid space).

You cannot declare a number-suit combination already claimed on the research board (by any player).

Scoring / Victory Conditions

Winning tricks: Score 1 point per trick won.

Largest connected group bonus: At end of round, count your largest group of orthogonally connected tokens on the research board. Score bonus points equal to the group size.

Prediction card: At the end of the round, reveal your face-down prediction card. If the number of tricks you won matches your prediction, score bonus points.

Paradox penalty: If at any point you cannot legally play a card (every possible number-suit declaration for your remaining cards is already claimed), you cause a paradox. The round ends immediately. You score negative points (lose points equal to your tokens on the board). Other players score normally.

The game plays over multiple rounds. The player with the most total points wins.

Special Rules & Edge Cases

• Trump suit: One suit is designated as trump each round. Trump cards beat non-trump cards regardless of number.
• You may declare any available suit when you cannot follow the lead suit, including trump (which is how trumps enter play).
• Paradoxes end the round immediately for all players.
• Connected groups are only orthogonally adjacent tokens (not diagonal) of the same player on the research board.
• With 2 players, use modified rules with fewer cards and a dummy hand.

Player Reference

Element	Points
Tricks won	1 per trick
Largest connected group	1 per token in group
Correct prediction	Bonus points
Paradox (cannot play)	Negative points (lose token count)

Key rule: You declare suit when you play — cards have no inherent suit Key constraint: No two players can claim the same number-suit space