What follows is a mock up for how a card game in real life would be played with actual cards. Assume that in any forum adventures and or video games, certain elements will be streamlined (such as "cardsmithing" actually making new cards instead of being laid on top of other cards
Each player has a "battlefield" that's made up of three rows of five. Defense cards in front, attack cards in the middle, speed cards on the bottom left second and armor cards on the bottom right three. The player chooses a player card and sets their deck below that. A d20 is used for actual "attacks." Each player starts with 200hp. The object of the game is to diminish a player's hp to 0 or have them run out of usable cards in their deck.
To start, a player must pick a player card.
Player cards will have individual attributes or skills assigned to them based on who is selected. They create a base stat. Each attribute will be color coded for easy reference (defense is green, attack is red, speed is blue).
As the game is played, each player may draw one card from their deck per turn, who starts the turn will be based on speed stat. A turn is ended when each player has placed the amount of cards they want down on the field. The three numbers on the field are added together and that is the player's final "level." Each player then rolls a d20 to determine succsessful attack or failed attack. Their level is added to the roll of the d20, and whoever has the higher roll wins that turn, taking however many points are assigned in their attack row's worth of hp from the other player. The other player's defense is also applied to determin final outcome. If there is an exact tie in rolls, the player with the higher attack row wins. Afterwards, the opposing player takes their turn and does the same. Then the round is over. Any card that has a once per round usage is discarded after each player has taken their turn.
A player can draw up to five cards and only have five cards in his or her hand at a time. If a player doesn't wish to place a card during that turn in order to save a card for later they can. If a player has five cards in their hand, in order to draw a new one they must discard at least one card. A player can choose to discard up to all five cards if they wish.
There is a fifth card type, elemental cards. They can be "cardsmithed" on top of other cards to create new cards (thus still only taking up one card spot on the field). Certain cards will have "formulas" on them that demand certain "ingredients" in order to cardsmith. For example, above the sword card would read "apply flame element to create fire sword (requires 1 flame elemental card)." Each elemntal card will have a nonspecific modifier number on it that adds to the effected card's points. If more than one elemntal card are used, whichever card is on top is the number chosen to add to the base number.
The idea is to create strategy (and some luck of the draw) on the three fields and how they can effect each other. A card could be created that's base stat is altered based on how high the player's speed stat is (a field probably forgotten about after the turns are established, though the turn order can change mid battle). Or another card might optionally cost negitive defense points for a boost in attack points, should the player be willing to gamble. Cardsmithing will create incentive to keep the more "useless" elemental cards when opening booster packs, as if enough are collected, newer, more powerful cards can be made. Hopefully the system can be refined enough to create a game even novice players can get into, while still allowing strategy in deck building for the more advanced player.
The game is meant to be very easy to explain and easy to learn, so that it can be picked up quickly. Games are meant to be short bursts of strategic fun that can be played 1v1, 2v2, 1v3, or however brave players feel they are with the strength of their decks (if played cooperatively, each team member rolls seperatly, then adds their final levels together).
This also (if used in a video game or forum adventure) allows for simpler combat with more player interaction. Instead of managing large skill trees or complicated menus and inventories, a player only needs to know whats in their deck as each item is self contained for ease of use.