User summary
ボブジテン (Bob Jiten) is a Japanese word game, very dependent on knowing the Japanese language very well.

In Japanese, there are Katakana words. These are very common, used in normal everyday speech, but the words are usually of foreign origin. And to describe a Katakana word, a Japanese person would normally use other Katakana words. The aim of this game is to discover the hidden Katakana word, but without using Katakana words to discuss it. For Japanese speakers, this is quite difficult. As an analogy, try to explain a worker placement game, but without using any game words. As soon as you say 'meeple', or 'VPs', you've lost.

The game uses a system similar to Insider. A player secretly identifies the hidden Katakana word from a deck. This player is the master, and tries to guide the others to identify the word. If a player gets it correct, the master gains 1 point, and the guesser becomes the master. But if the master gets called out for using a Katakana word, the accuser gains a point and becomes the new master.

The artwork for the game is by the publisher and design group Decoct Design.

The publisher says:
Our fellow friend Bob. He loves the Japanese language.

While studying the language, he just realized, that many foreign-origin words were not translated, but accepted as is, as a Katakana word.

Looking up the Japanese dictionary, he found out many of the Katakana words themselves were described using other Katakana words. "Now I have to create my dictionary of Katakana words, which never uses Katakana for a description!"

That was the beginning of the creation of the Bob-Dictionary : Bob Jiten(ボブジテン).

Publisher's summary
カタカナ禁止の連想ゲーム

日本語大好きな僕らの友人、ボブ。
彼は日本語を勉強する中で、多くの外来語が日本語には訳されず、カタカナ語として定着していることに気付いた。
日本語辞典で調べても、カタカナ語の説明にカタカナ語が使われている始末。
『だったらカタカナ語を日本語だけで説明する辞典を自分で作ろう！』
そんな考えから、ボブジテン作りは始まった。

In Extremis