Even though the fantasy VN circle Type-Moon are more well known for the Fate series nowadays, 2000's Tsukihime
was their first visual novel, and you can see how things got started. The feel and jargon of Nasu's world (Magic Circuits, Executors, the role of the Catholic Church, etc.) may possibly not originate here, but are liberally namedropped and begin to take form.
The game had a pretty engaging story, if more workmanlike than truly groundbreaking. The Near Side routes are an immense deal of fun, while the Dark Side routes are very emotionally compelling and make effective use of drama—though I did find Hisui's route quite dull in places. The mystery aspect, in all routes, was the most consistently engaging element throughout. The characters are also pretty likable, and you can even see shades of the personalities of Fate/stay night's characters in a few of them.
The main problem I found was with the pacing, though. Even for a visual novel, the game's routes run very long. Many of the scenes, but especially the sex scenes, are far too long, self-indulgent, and often unnecessary. Many of them are also repeated between routes with subtle changes as well, which can cause you to miss important info or backstory among all that filler if you skip.
On the technical side, for a doujin game, the art is pretty good. The character designs are pretty consistent with late 90s/early 2000s designs, and the sprites are varied and expressive. The backgrounds are mostly real images with filters, or drawn in important scenes, but they do create a pretty good aesthetic.
The music and sound leave a lot to be desired, however. Apart from the beautiful jazz piano title track, the music loops are EXTREMELY repetitive and bland, especially in the domestic scenes. (The music often helped the game to feel longer than it may have actually been.) Also, the sound effects are rare and rudimentary; better integration could have helped the setting to feel a bit more immersive.
Given that this is a doujin game though, I really can't be too hard on them over the technical aspects. Overall, I found this game was a good introduction to Type-Moon and its universe. Due to its length, however, it may not be a good first outing if you're just looking to get started with visual novels.