It's a relatively old game, so I'll put up here a spoiler so to remove potential confusion:

DDLC is a __horror__ game that contains some gore, death, and self harm content, as well as small fourth wall breaking, disguised as a Japanese Visual Novel style soft/hard porn game. The entire game is a figurative jumpscare. Which makes it technically true to call it a "disturbing and shocking" game, but not as in """disturbing and shocking""" as in the euphemism for pornographic. It is technically correctly rated and marked as such. It just doesn't say viewer discretion of what kind is recommended.

And also: a lot of these Japanese pastel colored things, Visual Novel games included, are in fact not intended for kids, especially under 15. It's not like picture books for 6-12 year olds. Audience gender distribution is often closer to 50:50 than what many assumes.

I'm intentionally not reading your post, but the "it's old so I can spoil it" is never an acceptable stance in a world where they keep making more people. The world doesn't begin and end with your experience.