Aya Kyogoku and Hisashi Nogami of the Animal Crossing: New Horizons development team revealed a few more details about how couch co-op and online multiplayer will work in Animal Crossing: New Horizons in an interview with IGN at E3.
The New Horizons demo on Nintendo Treehouse live stream showed Kyogoku and Nogami playing local multiplayer, each of them using a single Joy-Con to play. They revealed during the stream that up to four players could play this way and then confirmed to IGN that they’ll all be playing on a single screen, not split-screen.
Then, when it comes to online and local wireless, up to eight players can be on an island. This is doubled from New Leaf’s previous 4-player limit. And though there is a travel theme to New Horizons, Kyogoku confirmed you can’t set up a tent on a friend’s island. However, Kyogoku told IGN you can make up to eight playable accounts on one Nintendo Switch and they will be able to live on the same island. You cannot have multiple islands, however.
Source: IGN.com Nintendo Confirms New Details About Multiplayer in Animal Crossing: New Horizons