Players all start with 6 cards in hand drawn/dealt randomly just like any card game.

ROUND BY ROUND
Initiative is still done normally, though everyone plays a card face down and then everyone reveals what they played.

During each participant's turn, they play one card facedown that buffs all their defenses and play other cards to take their actions. At the end of their turn they draw two cards and add them to their hand and discard any cards of their choice until they have only 6.

PLAYING CARDS
During any "skill/combat resolution" they can play one of their cards. Each card has a value and a stat/style applied. They add their character's stat to the value of the card to determine their result. If the stat/style matches the action, they add +7 more than the normal value. They may also attempt an action without playing a card, simply using their character's base stat as the result.

The GM draws two random cards and picks one of the two to play in response and puts the other into their hand. If their hand is already full (GMs get 4 cards + 1 more card per player in the game) they can discard any number that they wish. If the GM's card value + monster/trap stat is equal to or less than the player's stat + card value, then the player succeeds. Otherwise they fail.

DRAWING CARDS
Whenever someone plays a card, they also draw a card after the action is resolved. If their single action requires multiple cards to be played, they can play only up to their whole hand before no more can be played and they must take only their base stat as a result until the end of their action, at which point they can draw cards to replenish their hand. Cards cannot be drawn outside of your turn/action, so if you can interrupt other character's turns, remember that you cannot draw cards to replenish until the END of your next turn/action.

DIFFERING VALUES
If the game has different values for different rolls, you may need to take average for one type of roll and only do cards for others or simply have a different value for different stats. For example, d20 games have a d20 for outcomes but have damage rolls to determine damage and healing. Such a game would always deal "average" damage and healing but use the cards for the d20 rolls. A deck of normal 52 bicycle cards would work.

Clubs 2-10 = Strength/Constitution
Hearts 2-10 = Charisma/Wisdom
Spades 2-10 = Dexterity/Intelligence
Diamonds 2-10 = Wild
A = 1
J = 11
Q = 12
K = 13

Example: Dwarf swings axe at wizard. Plays 6 of Clubs. Because they are using a Strength-based attack, this gives them +13 to their attack as if they had rolled a 13 (would've been only 6 if it weren't a Clubs). Because they already have +5 to attack and the wizard's AC is only 16, they hit (the wizard has only a +2 Dex and +4 Armor and played a 6 of clubs for defense, which gives their Str and Con +13 but all other defenses only +5 for a total AC defense of only 12). They do average damage. The wizard casts a wizard spell and plays a 9 of Hearts. This gives them only +9 to their attack as if they had rolled a 9 since wizard spells are Intelligence-based and require a Spades card for full effect.

SHOWING YOUR HAND
When you draw cards, you can choose to discard your entire hand and draw a new one, but if you do so you lose your action that round.

CHARITY
Instead of drawing a card, the lowest level character or character with the lowest current hit point total can pick a card from the discard pile of their choice and add it to their hand but cannot play it during that round and must wait until next round.

METAGAME ANALYSIS
The goal of the GM in this card game should be to save good cards for particularly difficult or challenging encounters. A fun way to play is for the GM to always play their lowest # card of the appropriate suite. This means the GM gets the poor cards out of the way but the good cards come out later, often making battles become more difficult the longer they last.
This message was last edited by the GM at 14:52, Wed 26 Feb 2020.