Alright, here's a story I've told a few times before:
Almost ten years ago, Chunsoft was working on a game called 9 Hours, 9 Persons, 9 Doors. While the gameplay itself is nothing special, just solving puzzles, its most notable feature was the plot. 9 people are trapped aboard a sinking cruise ship as part of some game, reminiscent of a Saw movie. The game plays with metatextuality by synthesizing various real-world theories, rumors, and philosophies with a few completely unique to the game's world in an attempt to pique the player's interest and fuel its own thesis.
As Chunsoft was working on their game, another company, Spike, was working on its own. DISTRUST would be about 15 students trapped in a high school trying to escape while playing a killing game. Like 999, it too was said to have been inspired in part by the Saw film franchise. Spike had their eye on 999, as the many similarities meant that 999's sales could be predictive of DISTRUST's success.
999 failed, and Spike began to reexamine DISTRUST. 999 was criticized for being too dark and violent, but also too intellectual. DISTRUST, at this point was already at a stage in its development where they couldn't just can it, so Spike instead altered some elements to make it more palatable for the Japanese. Characters became cuter, deaths were made less violent, dating sim elements were introduced, and the game's color palate was changed from predominantly gloomy greys and blues to what Spike called "Psycho-Pop".
DISTRUST, renamed Danganronpa, was a huge success. A short while later, Spike and Chunsoft merged. Now, the time for sequels came around. While Danganronpa was basically given free reign, Zero (aka Extreme) Escape were put on a tighter leash and encouraged to copy Danganronpa.
The new game, Good People Die (Virtue's Last Reward) would be less violent, have less immediate urgency (no 9 hour narrative time limit). Uchikoshi, the director and lead writer, wanted a rape scene, but was denied it by the Spike Chunsoft executives. The game has a cartoon animal mascot voiced by TARAKO, who would also voice Monokuma in everything after the Danganronpa spin-off. The game still failed.
Then came round 3. Both series were trilogies and ended in a very similar way. This is because the writer-directors behind both had become friends and had shared many ideas. While one was two anime series, the other was the last game, but everything else is extremely similar.
>for the first time in both series, timed bracelets put players to sleep
>villain/mastermind is criticized as being completely nonsensical in both, this was not a typical criticism for either series before
>both are far more violent than normal, each containing a chainsaw scene and other bloodbath-style scenes, atypical for either series before, for the pretty much the first and only time, Danganronpa 3 often uses red blood instead of the typical pink
It's pretty amazing how these two series have so heavily influenced each other throughout the years.