These are the rules as played at playsite
Spades is a four player trick game, much like Hearts or Bridge. The players are in fixed partnerships, with partners sitting opposite each other. Deal and play both proceed clockwise.
How partners are determined
Partners are determined by which seat you take at the table during the game creation phase. In other words, choose the seat directly across from the person with whom you wish to partner.
Rank of Cards
A standard pack of 52 cards is used. The cards, in each suit, rank from highest to lowest: A, K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3, 2.
The Deal
The first dealer is chosen at random. The cards are shuffled and then dealt singly, in clockwise order beginning with the player on dealer's left, until all 52 cards have been dealt and everyone has 13.
The Bidding
Each partnership must declare a bid, which is the number of tricks they expect to take. The first partner to bid in each partnership offers a "hint" bid, but it is up to the second partner to make the binding team bid. For example, one player may hint "3 tricks" and his partner will make an actual bid of "6 tricks." The team must then collectively capture six tricks to make their bid.
Blind Nil
Blind nil may only be bid by a player whose side is losing by at least 100 points. A blind nil bid is identical in requirements to a nil bid, but is declared before a player looks at his cards. The bidder must exchange two cards with partner; the bidder selects two cards to pass, and the partner then selects two cards to pass back.
The Play of the Hand
The player to the left of the dealer leads the first trick, which is normal except that spades may not be played by anyone, including the leaders.

The player who won the trick leads into the next. Any card except a spade may be led. Each player in turn must follow suit if possible; if unable to follow suit, the player may play any card. A trick containing a spade is won by the highest spade played; if no spade is played, the trick is won by the highest card of the suit led.

Spades may not be led until either spades have been broken (played on the lead of another suit) or the leader has nothing but spades left.

A side that takes at least as many tricks as its bid calls for receives a score equal to 10 times its bid. Additional tricks (overtricks) are worth an extra one point each (but this is not good news, see the "sandbagging rule" below.)

Sandbagging rule: A side which (over several deals) accumulates ten or more overtricks has 100 points deducted from its score. Any overtricks beyond ten are carried over to the next cycle of ten overtricks -- that is if they reached twenty overtricks they would lose another 100 points and so on.

If a side does not make its bid, they lose 10 points for each trick they bid.

If a nil bid is successful, the nil bidder's side receives 50 points. This is in addition to the score won (or lost) by the partner of the nil bidder for tricks made. If a nil bid fails (the nil bidder takes one or more tricks) then the bidder's side loses 50 points (but still receives any amount scored for the partner's bid, and the tricks won by the nil bidder count towards making the partner's bid.)

A bid of blind nil scores twice as much as an ordinary nil, 100 points if successful and negative 100 points if unsuccessful.

The game ends either when the absolute value of either team's score exceeds the score target (usually 250 or 500 points.) When the game ends, the higher score wins. For example, if the target is 250, the game ends when a team goes over 250 or below -250.