Bubblegum Crisis. No anime series is more '80s than you are. With its obvious influences from Blade Runner, The Terminator, and Streets of Fire, the series is everything you loved about the '80s.

Cyberpunk, neo-noir, and rock were combined to make an interesting story, but it was cut short due to internal politics between the two companies that were producing the series. 8 of the planned 13 episodes were created, and it just ends after the Knight Sabers get upgraded power suits
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Rumiko Takahashi has created some of the most beloved manga series in history. It's only natural that her works would be adapted into anime, but unfortunately, many of them are cut short due to their massive length.

Ranma is Rumiko's best selling manga series, but Studio Deen had to settle on a filler ending after working on 143 episodes. This doesn't stop Ranma from being a fun anime, but it's a shame the whole story wasn't adapted.
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Slam Dunk was one of the most popular series in Asia and Europe throughout the '90s. The slam jamming action and character driven moments were all very entertaining. However, Toei Animation ended the anime at 101 episodes, right before the Nationals Arc. They did work on four movies, but they were largely original material.
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Fruits Basket was the unfortunate victim of creative differences between manga creator Natsuki Takaya and Studio Deen.

Natsuki oversaw the majority of the anime adaptation since she was hurt with a wrist injury that prevented her from working on manga. Reportedly, she would butt heads with the anime director and vowed that a second season would never be made as long as Studio Deen has the animation rights to the series.
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talk about a bad adaptation. The series rushed many plot points and removed important characters from the story. Manglobe did a decent enough job animating the bloody action in Deadman Wonderland, but that's all the praise it can get. That cliffhanger ending just stings even more.
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Unfortunately, the anime was planned to go on longer than 16 episodes. Maybe Japanese viewers didn't like the out-of-sequence story telling, or couldn't get into the setting, but the series was cancelled with some plot lines dangling. It is still worth a watch, but don't forget to continue the story by reading the light novels.
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The TV series of Martian Successor Nadesico has an open ending, and the story was set to be continued with a trilogy of movies. This wasn't a terrible idea in itself. However, Martian Successor Nadesico was more on the lighthearted scale, but the movie took the series to dark and brooding territory. This didn't sit well with fans, and it was a massive flop which killed the series.
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Berserk is an epic, dark fantasy story filled with great characters and intense action. The 1997 anime series is one of the more graphic and depressing series. We see Guts rise through the ranks of the Band of Hawks and experience a great betrayal from his former friend Griffith. However, the series just ends after setting up the next arc.

One of Japan's darkest series will probably never see a full adaptation thanks to Japan's TV censorship laws and Kentaro Miura's constant hiatuses.
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Dark, disturbing, and surprisingly witty. Gantz may be focused on gore and nudity, but it dives into the human mind. Gonzo manages to do a decent job animating the first three arcs, but had to include a rushed filler final arc due to the manga's slow release schedule.
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Before Hiro Mashima made it big with Fairy Tail, he had Rave Master. Now, the manga is great and lasted for 35 volumes, but the anime adaptation was a mess.

Studio Deen butchered the story line and characters, and the adaptation was cancelled after 51 episodes due to low viewers and low disc sales.
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