Rules
Spades is played with 4 players and uses a standard 52 card deck (with the Jokers removed). The deck is shuffled and then dealt out with each player receiving 13 cards.

The player to the left of the dealer bids first. After bidding takes place, that same player leads the first trick. Afterward, turns rotate clockwise around the table with each player following suit of the original played card. If a player does not have a card matching the original suit, a different suit can be played. After all four players have played a card, the highest card of the original suit wins the trick and that player is awarded a point.

This pattern continues with the player who won the last trick leading the play for the turn. If the player cannot follow the original suit, they may play any other suit, including ♠, which may not be led until they are “broken”.
After all cards have been played, the round is over and each team's scores are tallied (described below). As a team, the objective is to win at least the number of tricks bid. Ace is high and ♠ is always the trump suit.
 

Bidding
After each player receives their hand, the player is presented with a bidding window.
The player must decide how many tricks they want to try to take. The bids placed for each team affects their possible score range. You may change the value by swiping left or right, tapping right or left arrows, or tapping the number next to the currently selected value. If you scroll all the way to the left, you see a special "Nil", which is a bid of 0. If you bid Nil, you are committing to not taking any tricks during the round; taking a single trick results in a point penalty for the team and avoiding tricks rewards the team with a point bonus.

In the first round of the first game, a player is selected at random to be the "dealer" and the player to their left bids first; in the next round, the player to the left of the dealer becomes the new dealer. Starting with the player to the left of the dealer, each player bids clockwise by stating how many tricks they expect to win that round. The individual bids are combined for each team; both players on the team are responsible for reaching the combined team bid.
A round begins after each player has placed their bid. At the start of a round or game, the player to the Dealer's left becomes the new dealer and the cycle is repeated.


Scoring
After a round has completed, each team's scores are tallied. The number of tricks taken by a team are compared to the number of tricks for which the team bid.

If a team successfully takes at least as many tricks as they bid, they receive 10 points for each bid they successfully took. If a team falls short of their bid, they lose 10 points for each bid they placed. For example, if a team bids 7 and taks 8 tricks, they gain 70 points for the bids they made and 1 point (and 1 sandbag if "Sandbag Penalty" is enabled in Settings) for the extra trick. Likewise, if a team bids 6 and takes 5 tricks, they lose 60 points. if a team takes more tricks than they bid, they gain 1 additional point (and 1 sandbag if "Sandbag Penalty" is enabled in Settings) for each extra trick taken; with "Sandbag Penalty" turned on, collecting 10 sandbags results in losing 100 points (or collecting 5 sandbags results in losing 50 points, depending on your Settings).

A special scoring rule is used for bidding Nil. If a player bids Nil and successfully avoids taking tricks, their team gains 50 (for a game of 250) or 100 points (for a game of 500); inversely, if a player bids Nil and takes even a single trick, their team loses 50 or 100 points. For example, if one player on a team bids Nil and takes 1 trick and their partner bids 6 and takes 5, the team loses 50 points for failing to go Nil and gains 60 points for collectively taking 6 tricks.

If a team reaches the Winning Score (500 points by default) the game is over and that team wins. If both teams reach 500 points in the same round, the team with the higher score is the winner. If both teams have the same number of points, another round is played to determine the winner. If enabled in the Settings, the “Mercy Rule” means that a team who reaches the -200 points ends the game and the other team wins.