Paved with Gold: an original card game

As with most children, the first card game I ever played was what we called Pelmanism, known outside England as Concentration or Memory. In Pelmanism you turn up two face-down cards and win them if they form a pair, otherwise you turn them face down again. It's that very simplicity that makes it a children's game. But this variation goes several stages further. Here, you can score for making any of the following -

pair (two cards of the same rank), scores 4
threes (three cards of the same rank or suit, or in sequence), scores 9
prime (one card of each suit), scores 16
colour (five red or five black cards, scores 25)

I very nearly called it Whittington, after the semi-legendary mayor of London who came to the capital intending to seek his fortune after being told that its streets were 'paved with gold'.

Cards and deal: From a 52-card pack deal 25 cards face down in a 5x5 square and stack the remaining 27 face down as a stock.
Object: To win cards by remembering the location of those whose position you have already seen and picking up one or more that form one of the above combinations.
Play: At each turn you pick up either one or two cards, examine them secretly, and either put them back or make a claim.

If you pick up one card you can claim to be able to pair it by turning up another card of the same rank, or to make three of a kind, a flush, or a run with it by turning up two more cards, or by turning up three more cards to make a prime with it (that is, one of each of the four suits), or by turning up four more cards to make five cards of the same colour (red or black). If successful, you win those cards and score 4 for a pair, 9 for a three-card combination, 16 for a prime, or 25 for five of a colour.

If you pick up two cards you can do any of the above except score for an accidental pair. A pair only scores if you announce it just before picking the two cards up.

If you make a false claim, in that the cards you turn up fail to match your prediction, all the cards of the claim are won by your opponent (or, if three play, whichever opponent you choose) and kept as bonus cards separately from their point-scoring combinations.

Cards removed from the square are replaced by the same number from stock so long as any remain.
Ending and scoring: The game ends when the stock is empty, fewer than nine cards remain in the square (otherwise they are bound to contain three of one suit), and one player claims that no more point-scoring matches can be made. The remaining table cards are turned face up and are won as bonus cards by the claimant if correct, otherwise by their opponent (or, if three play, by either opponent of the claimant's choice).

Each player’s final score is the total they made for combinations plus 1 for each bonus card they have won.