What is "Tokyo Ghoul:re"? There were events that happened in Tokyo Ghoul:re but didn't happen in the original show, like: 



Is Tokyo Ghoul:re different from the original Tokyo Ghoul?
Tokyo Ghoul:re is the sequel manga to Tokyo Ghoul. The Tokyo Ghoul manga ended in September of 2014 and was adapted into the first 2 seasons of the anime, though the second season, Root A, greatly diverged from the manga with significant differences but still attempted to have the same major events as the manga.

You can read about possibilities of why they did so in this question (be wary of spoilers in all the links here): Why did Tokyo Ghoul √A completely deviate from the manga? and for more details on the differences, you can read my answer or this post on reddit asking about the same thing.

Both the anime and the manga ended with spoiler:


   the ambiguous death of Ken Kaneki at the hands of Kishou Arima (as in he is believed dead, but it's not fully confirmed, though in the manga it leaned significantly heavier on the dead side with multiple holes in his head)


Tokyo Ghoul:re picked up 2 years after the events that ended Tokyo Ghoul. It's about Hiase Sasaki, a ghoul investigator and leader of the Q's squad, currently low ranking investigators that underwent a very special surgery. It follows Hiase, his squad, and his superior/supervisor Akira Mado (daughter of the investigator that was Amon's superior and partner investigator in the beginning of the series), and shortly after all that begins expanding on stuff from the original manga, as well as filling in the 2-year gap.