Creating a new card game can be as easy as taking an old card game and changing some of the rules. Just look at Hearts.
Hearts is a trick-taking card game for three to six players. It is best played with four players. The object of the game is to avoid taking Heart cards in tricks.
For each hand, the cards are dealt one at a time face-down around the circle as far as they will go equally. Extra cards are laid aside, unseen. The player with the Two of Clubs then becomes the first lead player.
The lead player lays down a card, and each player in turn moving clockwise around the circle lays down a card. Those cards must match the suit of the lead card if possible. The player playing the highest card in the suit that was lead takes the trick, and leads to the next trick. A Heart card cannot be lead until one has been played that does not match the lead card.
Heart cards taken in tricks each score a point. The player with lowest score when another player’s score reaches 100 wins the game.
New rules have been added over time to create new Hearts card games. A three card pass was added after the deal and before play. You pass three cards to a player, and a player passes three cards to you.
Another rule commonly called ‘Shoot the Moon’ was added. With this rule, if you take all scoring cards during a hand, you score zero points, and each of the other players score the total of all scoring cards in play. Or you subtract the total of all scoring cards from your current score.
One new rule made the Queen of Spades a scoring card worth 13 points, while another new rule made the Ten of Diamonds a scoring card worth minus-10 points.
With new rules came new names for some of these games. People now play Black Queen or Omnibus Hearts instead of Hearts.
So what can you do to create a new Hearts game?
You could change the rules to make all of the red cards scoring cards. Heart and Diamond cards would each score 1 point. Or you could make Heart cards each score 1 point, and Diamond cards each score minus-1 point.
Or you could change the rules so that the Two through Nine of Hearts each score two points, while keeping the Ten through Ace of Hearts each scoring one point.
Or you could add some rules from Crazy Eights to make Hearts more interesting. You could play a card with the same rank as the card laid down by the player to your right, no matter what the lead suit was. And you could play an Eight and change the suit of the lead card. (The Eight would belong to the new suit.)