As you might guess, the control pad moves Link. The B Button activates the sword, which, as always, you can hold down to charge up a powerful spin attack. The R Button is grab, and you can lift, pull or throw just about anything, from bombs to the other player! The A Button uses the item the player currently has equipped. Holding the L Button brings up a map, and the Start Button freezes gameplay for all players.

Items in 4 Swords are very well done. Each player can hold only one item at a time, but dotted around the levels are Item Pedestals. These allow the player to switch his current item for the one on the pedestal. You can do this by facing the pedestal and pressing A. Pressing the A Button at any other time activates the current item.
See the list of Items

Holding the L Button brings up a map, showing the location of the other players in relation to each other and the end of the level. You can hold L to view the map and still move and interact in the background, and the map background is clear so you can do this.

As you go through the game, you may pick up seeds. There are 3 types of seed: Razor, Armor, and Pegasus. Razor seeds increase your attack power, Armor seeds increase your defense power, and Pegasus seeds increase your speed. These effects last for the rest of the level, and are displayed on the same screen as the map, on the left-hand side.

When you start the level, you have 6 hearts, 5 of which are full. You can gain health from hearts, or fairies. A heart heals one heart of damage, while a fairy will heal you fully. When all players are on full health, all rupees you collect will be worth double. At the end of each stage, there is a Heart Container. The player who collects this will have one extra heart for the remainder of the level.

If you lose all your hearts, you must pay a penalty in rupees. This is 50 to start with, but every time somebody dies, this is increased by 50 rupees. If you do not have enough rupees to revive yourself, the game ends for all players and you are returned to the level select screen.

There are three different colors of Rupees in two different sizes each. Blue Rupees are more valuable than green ones; red more valable than blue. The small Rupees are worth 1, 5 and 20 Rupees respectively, and the large ones are worth 50, 100 and 200. If you collect a black rupee, some of your money will fly out, and you will have to recollect it.

There are also Rupee Shards hidden within the levels. On their own, they are worthless, but if you collect 4 of them, you can make a huge rupee worth 500 Rupees. Each player collects shards individually, and you can see how many you have by holding L.

There are four different levels, each based around a different theme. Sea of Trees is a foresty level, with lots of trees and grass. Talus Cave is an ice-based level, with large amounts of slippery ice. Death Mountain is a fire-based level, with much lava and fiery obstacles. Vaati's Palace appears only once you have beaten the other three levels. Each level is divided into two stages and a boss fight. The stages are main stages are a mixture of exploration, cooperation and competition, but in the boss fights, cooperation is vital.

After you complete a level, you will go to see a Great Fairy, who might give you a key depending on how well you did. If you got 1000 rupees, you are eligible for a Silver Key. Once 3 Silver Keys are earned, the path to Vaati's Palace opens.

However, after beating Vaati once, you can replay the earlier levels at a higher difficulty. The puzzles are more annoying and the boss fights made much harder. If you manage to collect 3000 rupees on this harder level, you can receive a Gold Key. With 3 Gold Keys, you can play through a harder version of Vaati's Palace.

And finally, if you manage to defeat Vaati on that difficulty setting, you can attempt to complete the first three levels on the hardest difficulty setting. If you manage to collect 5000 rupees, you will earn a Hero's Key. 3 Hero's Keys unlock the hardest challenge of Vaati's Palace.

While the rupee count displayed on the screen is a collective total, the game also records how many rupees individual players have collected. After each level, the player who collected the most rupees is awarded a Medal of Courage. After 10 Medals, a secret is unlocked in Link to the Past.