The Sims Castaway Stories (Wii): Single-Player Only

The Sims Castaway Stories on Wii is strictly single-player. It does not support local co-op or split-screen.

What "Multiplayer" Existed

• WiiConnect24 / Nintendo Wi-Fi Connection: You could exchange custom islands, households, and messages with friends online (Friend Codes required). This was asynchronous sharing, not simultaneous play.
• Service Shutdown: Nintendo Wi-Fi Connection ended May 20, 2014. All online features are now non-functional.

Wii Sims Games With Local Multiplayer

• The Sims 2: Castaway (Wii) — Also single-player only.
• The Sims 3 (Wii) — Single-player only.
• MySims / MySims Kingdom / Agents / Racing — All single-player.

No Wii Sims title supports 2-player local co-op. For couch co-op life sims, see Animal Crossing: New Horizons (Switch), Stardew Valley (multiplatform), or Disney Dreamlight Valley (Switch/PS/Xbox/PC).