When the picture returned, New Wirral was gone. In its place was a folder directory. And inside that folder was a single, new file:
New story content and challenges that expand the lore of the world.
that allows any two of its 100+ monsters to merge into a brand-new form. Since its May 2023 launch, the Nintendo Switch version has received significant free content updates and paid expansions that expand the world of New Wirral. Key Content & Version Details
Head to the Nintendo eShop now and join the cassette revolution – no piracy required.
If you dumped the files yourself, they are legitimate. If not, you may need to enable "Install unsigned code" in your CFW settings (Sigpatches).
The only legal way to use an NSP file is to dump your own purchased cartridge using a modded Switch. If you own a physical copy, creating your own personal backup ROM is legal in some jurisdictions (like the US under Fair Use, though it violates Nintendo’s TOS).
No article about Cassette Beasts is complete without discussing the DLC. If you are hunting for the full NSP, you want the DLC included.