Natto-Cat 1.4 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. We recommend checking the downloaded files with any free antivirus. This free program is an intellectual property of Exploding Custard Software. The program lies within Games, more precisely Arcade.
From the developer:
Natto-Cat is a completely free, unique Boulderdash style arcade game. Help cat agent RB51 navigate through caves filled with natto and collect cat snacks. (Natto is fermented beans, a Japanese food.) Each cave has a required number of cat snacks to retrieve before the exit elevator can be activated. Dangers include falling dried plums and walking, exploding bowls of custard.
You may want to check out more software, such as Palantir, Motherload or Tetris Revolution, which might be related to Natto-Cat.