This is really cute, I like it a lot! ^^
English speakers usually know this kind of game as "Mastermind."
I did find some errors. When viewing the research report in English for Phase 0, the text is cut off just above the "Notes" heading. It says "...and the subject is considered outwardly" and then stops.
Also, the text cuts off in a similar way when viewing the English research report for Phase 9. The text says "...further increasing the difference from the" and stops there.
In many of the English reports, there seems to be return characters (new lines) placed after a comma, which looks odd.
After clicking the "Gallery" button, the loading text says "LOADING REPOTES..." which should probably say "LOADING REPORTS..."