A chicken dies.

Technically, yes. A chicken is killed and used as a part of one of the murders.

Nope. One character owns a cat, but it's not seen in this game.

3rd chapter execution. they set it up so it looks like someone is about to be burned alive but instead she is hit by a truck.

One of the characters is shown to cut their leg to keep track of how many people they've killed, but the cutting itself never happens onscreen or during the events of the game.

One of the characters is murdered and has their wrist broken during a struggle, though it isn't seen on-screen.

When a killer is discovered and found guilty, they are executed through various methods. The first execution involves someone being beaten to death.

Two characters in chapter 3 die from their heads being smashed with a hammer/mallet. The scenes are bloody, but their heads aren't mutilated.

All of the main characters are under the impression that they have been kidnapped.

Some might argue technically no, but for the sake of trigger warning, yes. (Major story spoilers) Most of the characters are revealed to be approximately 18 years old near the end of the story, but that doesn't mean much when throughout the entire game they themselves and the player believe they're 16 or so years old.

(Major story spoilers) The first scene of the game is a man being killed in a space ship. Near the end of the game, it is revealed that this man was the father of one of the central characters.

There is a scene that has the main character, Makoto Naegi, showering

There are no ghosts, however there is extensive talk about them (mostly in the context of "this character thinks there is a ghost, we have to explain to them why there isn't")

I mean they're being watched 24/7 via cameras all over the school, I would consider that stalking.

A certain character "vomits" blood in chapter 4

There's no hospital, but there's a nurse's office in the school that gets visited a lot.

Not necessarily, but if you do Sakura’s free time events she mentions her first love Kenshiro, who has an unnamed terminal illness

It is mentioned that one of the characters cuts her leg (hidden by clothing) every time she commits a certain act. This is not shown.

Certain characters are shown panicking, especially Sayaka.

The very first scene has someone trapped in an iron maiden-styled rocket before he dies. This may or may not set off claustrophobia.

One character poisons herself in the forth chapter and another puts herself through all of the previous executions during the final chapter.

Technically, yes. The entire game takes place in a school in which they believe they have been trapped in and are being mentally manipulated into killing one another.

Yes but camera bobbing while you walk can be disabled in options!!

You don't see the actual birth, but there is an optional bad ending in Chapter 5 that shows one female character that has borne the children of 3 male characters. All of them are underage too...

There's no explicit nudity or p*********y but there's some sexual remarks and jokes, and an optional scene where the girls are shown in a bath house.

There’s an optional scene where three of the boys, protagonist included, peek into the bathhouse. A female character ends up calling another female character a s**t and another insults a girl on her chest size. One character lies about being sexually harassed.

I don't believe it's discussed in this game, but Leon's cousin Kanon has romantic feelings for him, which he does not reciprocate. Kanon is not featured in this game, but there is an incestuous relationship in a different game in the series (V3).

In the Japanese version, at least one character repeatedly uses the slur “R*t*rd”.

2 guys who are said to have fallen in love without realizing it" outside of the game both die.

There's a character who is AMAB, and presented as female to the group. The group discovers they were AMAB after their death, and immediately switch pronouns, without questioning if that's what they wanted to be called.

One character is overweight, and while it’s not commented on frequently, another character who dies rather early on calls him a fatty a couple times

There is a “bad ending” that could be interpreted as sad, but it’s more humorous considering it’s not really an ending, and after getting it the games takes you back so you can see the real ending

Junko kills her own sister.

Yes, the game has a lot of blood and gore due to its premise of a killing game. All the blood is bright pink instead of red, which for some people may be enough to not trigger them.

Almost all of the characters are under 18, and because of the multiple deaths it's safe to mark this as 'yes'

Not nuclear, but a bomb is set off in one of the later chapters.

Sorta? In the first scene of the game, a man is launched into space. His rocket ship goes up, plummets back down, and opens to reveal that he has become a skeleton during the process.

During an execution late in the game, a fire truck rams into a character, killing them.

there are guns in the school, though

Not a plane, but a space ship does crash early in the game.

Well, a fire truck, but yes,