Original Card Games by David Parlett
Players 4 (solo)   Cards 52   Type Rummy(-ish)
A sort of Rummy where you gift each other cards. (I always thought using 'gift' as a verb was a modern replacement for either 'give' or 'donate', but on checking I see it goes back to the 17th century, if not beyond.)
Cards and deal
From a well-shuffled 52-card pack deal 13 cards each, one at a time.
Object
To convert your hand into one containing any or all of the following melds or combinations:
• Flush: five or more cards in your longest suit
• Sequence: a sequence of three or more cards in the same suit (Ace counts high or low, enabling either AKQ or A23, but not both at once)
• Three or four of cards of the same denomination
• Twenty-one: four cards, one of each suit, with a total face value of 21. (Numerals count at face value from A=1 to Ten=10 and face cards at 5 each. Only one 21 my be declared.
Play
A game consists of up to three rounds, and each round consists of up to three swaps.

For the first swap in each round you each pass three unwanted cards face down to the player on your left, then add to your hand the three passed to you from the right.

For the second swap you each pass three unwanted cards face down to the player on your right, then add to your hand the three passed to you from the left.

For the third swap you each pass three unwanted cards face down to the player sitting opposite you, then add to your hand the three passed to you from the player opposite.
Knocking
Anyone satisfied with their hand at the end of the first round may ‘knock’ by laying it face down on the table, earning a bonus of 10 points at the end of play, provided they are the only player to knock at this stage. If three or four players knock, no more rounds are played. Otherwise round two begins.

Rounds two and three follow the same procedure, except that if only three players remain they make only two swaps (left, then right), and if only two remain they swap only once, with each other.
Score
Each player scores for their hand as follows:
• Flush: 1 point per card in their longest suit of five or more
• Sequence: 1 point per card in each suit-sequence of three or more
• Three alike scores 6, four alike 12
• Twenty-one: scores 7 points
• plus 10 bonus points for the only player to knock at the end of the first swap
Game
A game is four deals, or is won by the first to reach an accumulated score of 100.