The player controls the protagonists of Stardust Crusaders in a combination of Point and click adventure and classic third-person RPG. It is sometimes also referred to as a side-scrolling RPG.
Just like in the story, the game features Jotaro and his companions traveling the world together and battling enemy Stand Users to reach DIO. Like most RPGs, the player manages the heroes of Stardust Crusaders who can level up as they fight and whose health (named HP) and mental state (named "mental points" or MP) must be taken care of. If either HP or MP reaches 0, then the character is down or is too discouraged to fight. The game's Biorhythm System (バイオリズムシステム,Baiorizumu Shisutemu) also modifies how well a character can fight depending on their state of mind such as stress. The characters can also buy, use or equip items.
The camera is positioned in front of the controlled character and only a horizontal stripe at the center of the screen is used to display the characters and the environment. The character can thus only really move left or right in a given screen and go from screen to screen only a key points that allow traveling upward. The bottom half of the screen is used to display the faces of the characters and gameplay options while the top half displays dialogs. Other menus allow looking at detailed stats of the characters.
The player can do the following when in this mode:
When pressing the button "check", a cursor allows the player to select a given item on the background and investigate or use it.
The characters can also "talk" to NPCs that cross the screen. To do so, the player must press the "talk" button and select the NPC he wants to talk to. They can give clues to the player about what to do next.
The player can also manage the Items in the party's possession, notably having characters equip items that increase their stats.
The player can also look at Tarot cards so that Avdol can examine the items in the party's possession and tell which ones are particularly lucky.
Prior to a battle, the player selects one of the face-down cards offered through DIO's prediction and characters' abilities will change depending on which ones have been chosen.
The game uses a turn-based combat system. At the beginning of a turn, the player selects what actions each of the party's member must do and the turn unfolds. The characters can do the following:
Attacking deals damage to HP. The higher the MP of a character, the stronger his attacks are. Other items can boost the damage dealt. Attacks can be avoided.
Talking lets the character say a line taken from the manga. It is used to demoralize the enemy, damaging their MP or encourage the party, healing MP.
The "Prediction" command is used in conjunction with a set of tarot cards and tells the character's lucky item.
Using Items while activate a given item in the party's possession, enabling different effects such as healing. The player can also remove items from the characters or discard them into the trash.
Checking lets the character wait out a turn. The character does nothing but can unlock further actions.
Tactics are special actions that are unlocked after checking. Either the characters have an Idea! and perform a special action inspired by the events of the manga. Moreover, the character can perform a Guts attack, which is a particularly powerful version of the basic attacks.
The storyline used deviates somewhat from its source, likely due to system limitations.
"Dollars" are always used as currency, regardless of the country.
Members of the Speedwagon Foundation appear more frequently to provide clues and money for the heroes (if they sacrifice a day of their trip to rest).
Joseph routinely uses hisStand on TVs found throughout their journey in order to locate DIO. During these scenes, DIO can see and talk with the entire party. In the original story, he is only seen doing this once.
Vampires and zombies randomly attack the team in "dungeons" (they were originally scarce in Part 3). The few instances of Joseph's Ripple are absent from the game.
Polnareff first appears as a shop-clerk in a Japanese bookstore. Joseph suggests going there to find a book about DIO and Stands; in the original story, this information is passed through word of mouth by Stand users.
Forever's Stand Strength takes the form of a mansion instead of a boat, and is also in Japan; the fight takes place before Jotaro and allies even depart.
Dark Blue Moon attacks the party within a water trap inside a sewer route found in the mansion.
Midler is a stewardess on the same plane, and her Stand takes on the shape of the restroom's doorknob instead of a mug of coffee in the would-be submarine.
Steely Dan doesn't appear, though he is mentioned in the instruction manual. The Lovers, subsequently, isn't his Stand, but some sort of seed.
Enya the Hag is responsible for putting The Lovers into Joseph's head. Due to Steely Dan's removal from the game, Star Platinum and Magician's Red enter Joseph's brain along with Hierophant Green and Silver Chariot (in the original manga, it is only Hierophant Green and Silver Chariot who enter).
Oingo and Boingo are reduced to a supporting role and do not use their respective Stands.
Iggy appears at a pyramid in the desert. The part with Geb was almost entirely removed.
Alessi transforms Kakyoin, Joseph, and Avdol into children (in the original manga, he only transforms Jotaro and Polnareff). He also attacks them within a library, being supported by the Oingo Boingo brothers.
Jotaro's group obtain Anubis' sword from a strongbox in a pyramid. Khan is a merchant rather than a barber and negotiates with them to buy the sword. When they refuse, he steals it.
Chaka is a weapons dealer. He asks to take a look at the Anubis sword and is subsequently manipulated by it into attacking. Anubis is only used twice, but still maintains the same level of power.
Chaka and Khan's order of appearance is also reversed (in relation to the original manga).
Daniel J. D'Arby still plays cards but wins by playing normally. His entire scene is scripted as well; In order of Polnareff, Kakyoin, Avdol, Joseph, and Jotaro, the group plays him, losing without fail until it is Jotaro's turn, wherein he will win automatically.
Telence T. D'Arby battles normally as if his Stand was a power type (instead of betting and playing minigames).
Vanilla Ice is beaten normally (rather than being destroyed due to sunlight).
Nukesaku doesn't appear; DIO is already waiting for the main party.
Jotaro gains the ability to move through stopped time only after he wears a special school uniform for it found in DIO's mansion (in the original manga, he does this naturally).
Kakyoin, Avdol, and Iggy do not die and instead survive with the rest of the group at the end.