DQ9 EncyclopediaThe essentials
- Together: up to 4 consoles side by side, no internet. The guest follows the host's adventure; experience goes up by 10% per extra player.
- Over the internet: impossible on DS and 3DS. On PC, melonDS links two consoles on the same computer or the same network; at a distance, a virtual private network may work between nearby friends, with no guarantee (Multiplayer with melonDS).
- Online services (shop, Wi-Fi quests, special guests): shut down by Nintendo in 2014, reopened by fan servers; see Online content.
What the game code does when playing together (up to 4, locally), and what became of the online services.
In another player's world (guest)
- Quests: no quest of the game is offered in someone else's world (only downloaded quests remain visible).
- NPCs: 452 lines are reserved for guests; none gives an item. Gifts are received in your own world.
- Sparkly spots: the guest sees the host's (same group, same sparkles); only the host advances their respawn.
- Battles: the guest follows the host's battle; afterwards, it only advances the quest tied to that battle. It cannot steal quest items (Half-Inch).
- Sterling's whistle: no sound in someone else's world. Watcher's wings: given to the guest, they take it back home.
For everyone
- Experience: ×1.1 per extra player (×1.3 with four).
- Holy water, Vanish: each player's effect is shared with the other consoles.
Online services
- The DQVC (shop), special guests and Wi-Fi quests went through Nintendo's Wi-Fi service, shut down on 20 May 2014. Since late 2018, fan servers have revived them (today AltWFC; see the online content FAQ); Wi-Fi quests can also be unlocked with a code on an emulator.
- 167 items are only obtainable through these services: “Online only” tag (Rarity filter on the Items page).