Gridcannon

Full rules

1. Overview
2. The cards
3. Setup
4. Placing a royal
5. Playing a turn
6. Attacking a royal
7. Ploys
8. Cards you can't place: armour
9. No royals on the table
10. End of the game
11. Scoring
12. Tips for beginners
13. Variants

Overview

Gridcannon is a solo card game about a revolution. You lay out a 3×3 grid of number cards. The royals – Jacks, Queens and Kings – appear one by one and take up positions around the grid. To kill a royal, you place a card at the far end of its row or column: the two cards in between fire at it, and if their values add up to its health, it falls. Kill all twelve royals and you have won.

• Players: 1.
• You need: one standard deck with both jokers (54 cards) and a table with room for a 5×5 square of cards.

Designed by Tom Francis, with the armour rule by Chris Thursten (2019) – original rules: Gridcannon (blog post). Our text follows the revised version 2.

The cards

Setup

1. Shuffle all 54 cards and hold them face down: this is the draw pile.
2. Turn over cards one by one and lay them face up in a 3×3 grid – three rows of three, left to right, top to bottom. Every royal, Ace or joker you turn over goes aside instead; keep turning cards until the grid holds nine number cards.
3. Place the royals you set aside around the grid (see Placing a royal).
4. The Aces and jokers you set aside are your first ploys: keep them face up next to you.
5. If you like, replace one grid card: put it at the bottom of the draw pile and fill its place with the next card (a royal, Ace or joker is dealt with as in play, and you draw again).

Around the grid there are 12 places for royals: three along each side, one next to each outer grid card. A corner card of the grid touches two of these places, one on each side.

Placing a royal

A royal goes into a free place next to the grid card it is most similar to. Only the top card of each grid stack counts:

1. the highest grid card of the same suit;
2. if there is none: the highest card of the same colour;
3. if there is none either: the highest card of all.

If two cards are equally similar, or the most similar card is a corner (which touches two places), you choose. A place with a dead royal is not free – a royal can never be placed there again. The rules don't say what happens if every place next to the most similar card is taken; we suggest using the next most similar card.

Example: In the picture, the K♥ was placed next to the 9♥ – the highest heart. The 9♥ is a corner, so it could have gone above it as well. The Q♠ went next to the 6♠, the highest spade.

Playing a turn

Turn over the top card of the draw pile:

• A royal: place it as described above.
• A number card (2–10): you must put it on the grid, on top of any stack whose top card has the same or a lower value – suit doesn't matter. The stacks grow as the game goes on; only the top card counts.
• An Ace or a joker: put it face up with your ploys.

Attacking a royal

When you place a number card on the grid so that a living royal sits at the other end of that row or column – with exactly two grid cards between them – those two cards attack the royal. The card you just placed doesn't count; it only fires them. Add up the values of the two (top) cards:

If the total is at least the royal's health, the royal is killed: turn it face down but leave it in its place. Otherwise nothing happens (the card stays where you placed it).

A card placed in a corner can fire along its row and its column at once. A card placed in the centre never fires – no royal is two cards away from it.

Example: You turn over the 5♣. It may go on the 4♣, the 3♠, the 2♦ or the 5♥. You place it on the 3♠: the K♥ is at the other end of that row, and between them are the 9♥ and the 7♥ – both hearts, 16 in total, at least 13. The King is dead.

The Q♠ is harder: if you placed a card on the 4♣, the 10♦ and the 6♠ would attack, but only the black 6♠ counts – 6 is not enough. Put a black 10 on the 10♦ first, and the next card placed on the 4♣ fires 10 + 6 = 16 at the Queen.

Ploys

You may use a ploy at any time – even after turning over a card and before placing it. A used ploy is turned face down; each works only once.

• Extraction (Ace): pick up one whole stack from the grid and put it face down at the bottom of the draw pile. Its place is now empty. The rules don't say what an empty place counts as; in the first version of the game it counted as 0, so any number card may go there and it adds nothing to an attack.
• Reassignment (joker): move the top card of one stack to another stack where it could legally be played (same or lower value on top). This move can fire an attack just like a normal placement.

Cards you can't place: armour

If a number card fits nowhere and you have no ploy left (or none that helps), it becomes armour: lay it next to the living royal most similar to it – the lowest royal of the same suit, else the lowest of the same colour, else the lowest royal. Armour adds its value to the royal's health, and armour stacks.

Example: A King of hearts with a 3 as armour has 13 + 3 = 16 health.

If a Jack or Queen reaches 20 or more health, or a King 19 or more, the designer counts the game as lost: two cards can hardly beat it any more (a Queen needs two 10s of her colour, a King the 10 and 9 of his suit, lined up exactly).

No royals on the table

If all royals on the table are dead but fewer than twelve have appeared, turn over cards into a face-up pile until a royal appears. Place it, then put the cards you turned over at the bottom of the draw pile, and carry on.

End of the game

• You win as soon as all 12 places around the grid hold a dead royal.
• If the draw pile runs out before that, use any ploys you have left to rescue the situation (an Extraction puts cards back into the draw pile). If you have neither cards nor ploys left, you have lost.
• You also lose when a royal's armour makes it unbeatable (see above).

Scoring

If you win, your score is the number of ploys you haven't used. The best possible score is 6 (four Aces and two jokers).

Tips for beginners

• Build lines, not piles. Before placing a card, look at which rows and columns point at a living royal and which two cards would fire.
• Mind the colours. A Queen or King ignores cards of the wrong colour or suit – put high cards of the right suit in the middle of their lines.
• Keep low cards playable. If every top card is high, a small card has nowhere to go and becomes armour. Leave a low stack or two open.
• Save the ploys. They are your score and your emergency exit; an early Extraction often costs you a perfect game.
• Watch where royals will land. A high card of a suit attracts that suit's royals to its side of the grid.

Variants

All optional.

• Empty centre (the original set-up): deal only the eight outer grid cards and leave the centre empty; any number card may be placed there first. It protects you against a bad deal – the designer added it to the first version for exactly that reason.