Ninja Ryuukenden

♫ Subarashii chin chin mono
Kintama no kami aru
Sore no oto sarubobo?
Iie! Ninja ga imasu ♫

Only old school ninjas that don't shy away from gore violence and graphic nudity.
Your talking no jutsu has no power here!

♫ Hey, hey, let's go! Kenka suru
Taisetsu na mono protect my balls
Boku ga warui so let's fighting
Let's fighting love! ♫

Before the likes of Saint Seiya, Dragon Ball Z and Pokemon conquering the kids in the west, it was actually Akira that opened the door and made people realize that the cartoons coming from Japan weren't what you would expect from Disney or your TV channels.
A huge flood of VHS tapes came showing animations with mature themes, absurd plots, and enough graphic sex and violence to make parents freak out... what a glorious time!
They don't make cartoons like this anymore.

This is a comprehensive list with stuff from very good to very trashy, but all in the same spirit.
Some early 00's also included.

ps: I also recommend, but can't include here, Kage (OVA).

Glorious 80's and 90's (Sci-Fi, Neo-Noir and Crime Drama)
https://myanimelist.net/stacks/30604

Every cinema or direct to video anime film that came out in 1991.

1990: https://myanimelist.net/stacks/34459
https://myanimelist.net/stacks/34460
1992: https://myanimelist.net/stacks/34702
https://myanimelist.net/stacks/34703

Part 2: https://myanimelist.net/stacks/34463

Disclaimer: There are a few hentai movies, that could be counted as well:
- Choujin Densetsu Urotsukidouji 2 (1991)
- Koushoku Ichidai Otoko (1991)
- U-Jin Brand (1991)
- Violence Gekiga Shin David no Hoshi: Inma Densetsu (1991)

Games which are not Visual Novels.

One per franchise

Only including anime that came out between 1973 and 2001.
In the description of each anime I've included at least one reference to when/where they show up (but in many shows they show up frequently)
Work in progress. Let me know if you find an anime that includes the twin towers with episode # and timestamp if possible.