The most stable method is using via USB (MTP Responder): Connect your Switch to your PC via USB. Launch DBI on your Switch. Select Run MTP Responder . On your PC, open the "Switch" drive in File Explorer.
Ensure your system firmware version is compatible with Update 1.2.1 (typically version 15.0.0 or higher is recommended for this specific update). SPLTOON3-(USA)-NSwTcH-NSP-Update121-Ziperto.rar
Right-click the file and select or Extract to folder . The most stable method is using via USB
This specific file is an Update , not the base game. You must have the base version of Splatoon 3 already installed for this to work. SPLTOON3-(USA)-NSwTcH-NSP-Update121-Ziperto.rar