Gridcannon is a solitaire game that uses a traditional deck of cards with jokers. The game was made by Tom Francis and Chris Thursten in 2019.

In the game you have a 3x3 grid of number cards and around it you have face cards. The face cards are called royals and the goal of the game is to assassinate all 12 of them. If you manage to do this you win the game.

You can see Tom's design and rules for playing Gridcannon here.

How to play Gridcannon With Playing Cards.

Below are the rules on how to play the digital version.

3x3 Inner Grid

The 3x3 inner grid it where numbered cards from 2-10 can be placed. Number cards can only be placed on cards of equal or lower value.

12 Royal Slots

The outer 12 grid slots are the royal slots where the face cards Jack, Queen & King can be placed. Royals must be placed next to the numbered card most similar to it

Deck Area

The deck area has 5 different deck. Discard, Deck, Hand, Aces & Jokers.

Moving & Placing Cards

A card that can moved will have a green highlight around it. Drag the card to move, when you do all valid slots that the card can be moved to will be highlighted with a black tint and outline. Drop a card unto a valid slot to move it there.

Targeting & Attacking

Dragging a numbered card into a valid slot will highlight the attack that it will make if it is dropped there.

When dropped it will fire the payload at the royal slots opposite it. The payload is the sum of the 2 cards between the dropped card and the royal. In this case 5 + 10 = 15 which is greater than the Jacks value of 11 .If a valid attack with enough damage is done the the royal is defeated and flips over. Kings require both payload cards to be the same suit as the King, Queens require that both payload cards are the same colour as the Queen. Jacks will accept any suit or colour in the payload.


If a numbered card has no valid moves then it must be added to the most similar Royal to increase the armour of the royal. Armour adds to the Royals value so a greater attack is required to defeat them. Using Ploy cards can prevent the need to add armour.

Aces (Ploy 1)

(Extractions): These can be used to shuffle a stack of cards from the numbered grid back into the deck, this leaves a blank slot on the grid that any numbered card can be played onto.

Jokers (Ploy 2)

(Reassignments): These can be used to move the top card of a numbered slot to another numbered slot, the reassigned top card must follow the normal rules for placing a numbered card and must be placed on a slot with a card value of equal or lower value.

Viewing Number Of Cards In A Slot

Tapping/Clicking on a slot will show you how many cards are in a slot, this can be important to know when using Aces, so you know how many extra cards you are adding to the deck, it also is good to know how many cards are left in the deck to make sure you don't run out and lose.

Winning & Losing

The game is won if all the royals are defeated. The game is lost if there are no cards left in the deck and no ploys left to play. The game is lost if a royal becomes too powerful to defeat, this happens if a royal gains enough armour that it's value plus armour exceeds 20, since the most an attack can be made for is 20.