Tsukihime Complete Collection

The Tsukihime Complete Collection is a collection of all 3 of the games in the Tsukihime series, all versions are for PC.

Info

The full list of the games included are:

Something important to note is that all three of the games are 18+, meaning they contain H-scenes. However, the scenes can be skipped no worries. The Tsukihime Remake is all-ages, with the H-scenes removed.

You do not need to read the original Tsukihime to read the Remake, but reading the Remake does not make the original game obsolete! Additionally, as this is being written, Tsukihime Remake is not only incomplete, covering only the first two routes of the original game (with the others being planned to be covered in the Remake's sequel), but is also not available entirely in English. Currently, translation is partially complete and being handled by Tsukihimates. View their progress and download the partial patch here!

Tsukihime

Genre: Contemporary Fantasy, Vampires, Branching Plot, Bad Endings

Content Warnings: Sexual Assault, Incest, Abuse, Suicide, Underage Sexual Content

Length: ~40 hours

This story is about a young boy named Tohno Shiki who, after experiencing a traumatic accident, wakes up in the hospital with the ability to see lines and cracks in every surface and being. These lines, when traced with any sharp or blunt edge, will be permanently cut. As he is forced to see these lines everywhere, Shiki is distraught until he meets a mage girl who gives him glasses that allow him to live a normal life.

Years later, after living in a relative's home, the death of his father has him summoned back to the mansion he left years ago. There he must learn to live with his younger sister and two maid girls.

One day Shiki's life takes a turn for the worse when, on the way to school, he meets a blonde woman and he's overcome with the urge to kill her.

The recommended route order is Arcueid > Ciel > Akiha > Hisui > Kohaku. None of the routes are skippable!
Full Guide (Fuwanovel)

Tsukihime PLUS-DISC

Genre: Contemporary Fantasy, Vampires, Omake, Fan-Disc

Content Warnings: N/A

Length: ~1 hour

This is a fan disc of Tsukihime containing one short visual novel story, two omake stories and other fan materials.

Akira Seo, an underclassman of Tsukihime's Akiha Tohno, becomes acquainted with someone calling themselves Shiki Tohno, and together they set out to solve the mystery of a recent series of murders.

Kagetsu Tohya

Genre: Contemporary Fantasy, Vampires, Time Loop, Branching Plot, Lots of Endings

Content Warnings: Incest, Sexual Content Involving A Character Who Appears Underage, Non-Consensual Drugging

Length: ~15 hours

One year after the events of Tsukihime, Shiki Tohno is a victim of an accident. After this accident, Shiki awakens into a strange dream wherein he repeats the same day over and over. There are infinitely many endings to the day, but it always begins anew after each day. Eventually, Shiki discovers that he must find Len, the creator of the dream, if he wishes to escape.

You will need this.
Full Guide
There is also a flowchart but is honestly more harmful than helpful in this case.

(Click to enlarge!)