Iota is a compact grid-building card game (famously sold in a tiny tin) in which players extend a shared tableau of cards so that every line stays internally consistent: in each line, the cards' colors, shapes, and numbers must each be either all the same or all different. Score the value of every line you touch, and chase four-card 'lots' for doubling bonuses.

How to Play Iota

Components

• 66 cards total: 64 unique cards plus 2 Wild cards.

• Each non-wild card shows three properties: a color (red, yellow, green, or blue), a shape (circle, square, triangle, or cross), and a number (1, 2, 3, or 4). The 64 unique cards are every combination of 4 colors x 4 shapes x 4 numbers.

• A Wild card substitutes for any other card and has a face value of 0 points.

• You also need pencil and paper to keep score.

Setup

1. Shuffle and deal 4 cards face down to each player (look at them but keep them secret).

2. Stack the rest face down as a draw pile.

3. Flip the top card face up in the center to form the starter card.

The core rule: what makes a valid line

A line is 2, 3, or 4 cards in a straight row or column with no gaps. In a valid line, each individual property is either all the same or all different across the cards:

• Are the colors all the same or all different?

• Are the shapes all the same or all different?

• Are the numbers all the same or all different?

If the answer is "no" to any one of those three questions, the line is illegal. Maximum line length is 4 cards. A completed 4-card line is called a lot.

Your turn

On your turn, take one of two actions:

1. Add 1, 2, 3, or 4 cards in a single straight line, connecting to card(s) already in play.

   • All cards you play this turn must lie in one straight line, and at least one must connect to the existing grid.
   • Although you play into a single line, your placement may create or extend additional lines running the other direction; every line you create or extend must be valid.
   • You may extend a line by adding to either end.
   • Record your score (see below), then draw back up to 4 cards.

2. Pass, and trade some, all, or none of your hand to the bottom of the draw pile and draw replacements.

Wild cards

A Wild card stands in for any card and is worth 0 points. You do not have to name what a Wild represents when you play it, but it must represent a consistent card if it is part of two lines. You may also "recycle" a Wild already in play before your turn by swapping it for a matching card from your hand, then replay that Wild later.

Ending the game

The game ends when the draw pile is empty and one player plays their last card. That final turn's points are doubled. The player with the highest total score wins.

Sum the face values of all cards in each line created or extended on a turn; a card in two lines counts twice; Wild cards count as 0. Multiply the turn's total by 2 for each four-card lot completed, by 2 again if all four hand cards were played, and the final turn (deck empty + last card played) is doubled. These multipliers stack. Highest cumulative total wins.

Record each player's Total Score as the authoritative outcome. lots_completed is a diagnostic count metric only: because completing a lot retroactively doubles a whole turn's score and the all-four-cards and final-turn doublings stack on top, lots_completed never sums into Total Score. The deck_size knob (full vs. half deck) is a match param on this ruleset; it only changes game length and is not separately scored.