How to play Spades

A card game for four, with you and a computer partner. Bid how many tricks you will take, then make your bid.

The rules, step by step

There are four players. You and North (across the table) are partners against West and East. Everyone is dealt 13 cards. Spades are always the strongest suit.
First everyone bids how many tricks they expect to win. Choose a number and press Bid. Your bid and your partner's are added together.
A trick is one round of cards. The first player puts down a card, and everyone else must play a card of the same suit if they have one.
The highest card of the suit that was led wins the trick. But if anyone plays a spade on a trick that is not spades, the highest spade wins instead.
Spades cannot be led until one has been played, unless that is all you hold.
If you and your partner win at least as many tricks as you bid, you score 10 points for each trick you bid. Win fewer and you lose 10 points per trick you bid.
Bidding Nil means you try to win no tricks at all. If you succeed you score 100 points, and if you do not you lose 100.

You bid 3 and North bids 4, so your side needs 7 tricks.

If you win 7 tricks, you score 70 points. If you win 8, you score 71: the extra trick is worth a point.