I mentioned a playing card combat system in a post last week (There is No One True Way -- A Rant) and promised more information, so here we go. Unfortunately, I never saw this system in play. I was told about it by one of my players. One of his college DMs used it for his OD&D game. Unfortunately, my friend wasn't big on mechanics so I don't know exactly how it worked -- especially from DM's side of the screen.
The combat deck consisted of the court cards from one deck of cards, two jokers per player, and one deck of playing cards (numbered cards only) per player in the game. The cards were shuffled before each combat. Players drew a hand of cards -- three cards plus one extra card for every 3 levels (4 levels for clerics, 5 levels for magic-users). An attacking player would play one card:
If it was a number card, that number plus a bonus depending on the character's level and class was compared to the target's AC on a to-hit table to see if the hit did any damage.
If it was a court card, the player got some bonus (or his opponent got some penalty) depending on the specific card. (e.g. opponent knocked prone, opponent disarmed, etc.)
If it was a joker, the character automatically hit.
Multiple cards could be played if they formed a set (pair, three of a kind, four of a kind). This represented a flurry of blows. Each card was checked to see if it hit with every additional hit getting a +3 to hit (e.g. a three of a kind attack would would be three blows, one normal, one at +3, one at +6)
At the end of his combat turn, the player would draw one card from the deck. Discarding to reduce his hand to the number of cards allowed by his class and level if needed. (Yes, this apparently did mean that playing multiple cards reduced the size of your hand.)
When attacked, a player could could play a joker or a court card to parry a hit.
I have no idea how this worked from the DM's end. I was told the DM used cards just like the players did. However, I can't imagine the DM tracking a hand for each of ten or twenty monsters. Perhaps the DM had a single very large hand (perhaps determined by number of monsters)?