The Golden Sun series utilises multiple Gameplay Mechanics and Modes. Most of can be found in some form in virtually any game of the role-playing genre, the following article describes them as they apply to the Golden Sun series specifically.
For a primer on how Golden Sun games' approach to the Role-Playing Game genre is similar to and is different from the norm, and technical problems the new player may face see General Gameplay Concepts and Troubleshooting (GBA titles) and General Gameplay Concepts and Troubleshooting (DS titles).
Main article: Adept
The player takes control of a party of between one and eight (but usually four) characters who have the ability to utilise magic (Psynergy). These characters are referred to in-game as Adepts. Each Adept has powers of one of the four Elements, wind, water, fire and earth (referred to in-game as Jupiter, Mercury, Mars and Venus respectively) Over the course of the game, the player assumes the role of the main character (either Isaac or Felix for Golden Sun or The Lost Age respectively), and as such, this Adept is not given any scripted dialogue in-game, instead only being able to choose from yes-no inputs that the player can select from (though these are largely trivial decisions). At the end of The Lost Age, both Isaac and Felix leave player control and are hence given scripted lines.
In-game, an Adept's abilities are largely defined by a set of statistics, having RPG staples such as, Attack, Defense, HP, etc. These generally grow as the Adept defeats more enemies and gains experience by defeating enemies in battle.
Two notable exceptions are the availability of Utility Psynergy (magics that can preform environment-altering tasks, such as lifting boulders) and Djinn. Utility Psynergy is generally only obtained by gathering the relevant items, and thus withholding these items until certain events are completed is way of controlling the player's progress through the games.
Main article: Djinn
Djinn are creatures that are spread across the world (referred to in-game as Weyard), which augment an Adept's powers. As with Adepts, Djinni belong to one of the four elements. Djinni placed on a player are referred to as "Set" Djinni. These Set Djinni provide a simple statistical boost to the player. Furthermore, each Djinni has a unique ability that can be called upon in-battle to provide support (referred to in-game as "Unleash"ing the Djinni), such as an attack or a healing ability. Once called upon, Djinn go into a mode called "Standby", wherein they cease to give statistical bonuses, nor can they be unleashed, but each Djinni on Standby generates a separate resource which can be called upon to "Summon", that is, to cast what amounts to some of the most powerful attacks. Once a summon has been called, the Djinni that were depleted and placed on "Recovery" mode, wherein they cannot be used at all, either for Summons, Unleashes or statistical bonuses. Each turn in battle, one Djinni returns from recovery to set to allow the cycle to repeat. Outside of battle, Djinni can be swapped between Set and Standby at will, but will only return from Recovery to Set after a period of time has elapsed.
Also of note is that when Set, Djinn can have the effect of altering an Adept's Class, which can have many drastic effects on the Adept's natural abilities.
This Djinn system is perhaps the most unique aspect of Golden Sun's gameplay.
Main article: Weyard
The world of Golden Sun is Weyard. It's large and has several continents, but instead of being a globe, Weyard is flat; the edge of which is called "Gaia Falls," where water dumps eternally into the abyss. ("Well," says the old Apojii Islands villager, "at least Gaia Falls will put an end to a few silly arguments. After all, if it's got an edge and you can fall off it, the world is clearly FLAT!") The original Golden Sun explores only two large central continents, Angara and Gondowan specifically, while The Lost Age focuses on the continents and islands found across the seas. The civilizations spread throughout are generally small and are nearly devoid of technology, as indicated by how a sailing ship is a cutting edge innovation. Legends tell, however, of the "lost age of man," when Alchemy was commonplace and the world and technology flourished. This age nonetheless led to disaster owing to the inevitable overuse of power, which threatened to destroy all Weyard. Bold action led to using the Elemental Lighthouses to seal away Alchemy forever. In the time-frame of the first two games, some seek to restore this power.
Dungeons and Towns
In Golden Sun, as with many RPGs, travelling around consists of walking through a world map to reach individual locations. In general, these places can be sorted into two groups, Towns and Dungeons. Towns generally contain an Inn (where the player can pay Coins to heal their party), several Vendors (shops that sell various items), a Sanctum (which cures several specific status conditions) and several houses. Dungeons are basically all other locations. They are generally forests, deserts, caves, buildings or other such setting. Typically, a dungeon involves the player heading toward a destination, solving puzzles (such as rolling logs or aligning pillars) along the way. To complete these tasks, the player will almost always have to make use of some kind of Utility Psynergy. At the end of each dungeon, the player will generally be rewarded with a new item that is necessary to complete the game.
Main article: Battle
Golden Sun utilises a turn-based battle system, where the player chooses from a series of commands to fight with having the options; Attack, Psynergy, Djinn, Summon, Item and Defend to choose from. The player is also able to Flee from most battles as well as view information on their party via the use of the Status command. Later on, the player gains the Switch command, which allows them to decide which of their Adepts will partake in battle.
Battle is usually undertaken in random encounters, where by walking in the overworld or through (most) dungeons, Monsters will appear at random to fight the player. These appearances can be made more common by using the Lure Cap or less common through the Sacred Feather item or the Avoid Psynergy.
The exception to random encounter battles are scripted Boss battles, which generally occur upon completion of their relevant dungeon.
Although the system itself is fairly generic, Golden Sun's battle system has received high praise for the excellent graphics employed.
Although no option is given on the first playthrough, in the second game, two other modes can be accessed once the game has been completed. Easy Mode is where the player retains all stats and coins from their completed save file and is allowed to play through the game again, naturally at a higher level, thus making it significantly less difficult. Hard Mode reverts the player to their default starting stats and increases the toughness of the game's enemies, thus making the game significantly more difficult. No reward is given for completion of either mode specifically.
Main article: Battle Mode
Accessed from the main screen, the Lobby allows the player to fight either against a gauntlet of monsters that have been scaled to the player's level, or another player, depending on whether a Link Cable has been inserted.
It also gives access to the Sound Test in The Lost Age. If the player talks to the woman in the lower-left of the screen while holding a shoulder button, they will be able to hear songs from the game. All songs only become available once the game has been cleared once.
Main article: Password
The Password function allows the player to send data from Golden Sun to The Lost Age. This is accessible by pressing R, left and start in the opening menu of Golden Sun.