Thoughts on the anime adaptation:
The following content won’t spoil you unless where explicitly marked as spoiler. However it partially takes away the general directing of the show. You’re free to skip it if you’re worried.
First of all I want to say that the anime adaptation was decent, and overall I think Production I.G. managed to produce an enjoyable show. I also want to state, however, that I personally was unable to read the VN, as I simply don’t know Japanese. That’s why I’ll solely reflect on what my experience with the anime was, and what I’m aware of about the Visual Novel. I’ll also argue based on the Steins;Gate subreddit, as it features a wiki which a good amount of effort was put into and I trust the ones responsible for it. While being critical, I neither intend to, nor consider it justified to degrade the anime as „failed“. It’s still a good show, despite all its flaws.
The direction itself
The Visual Novel is organized in so-called “Phases”, which appear to be the chapters. As far as I’m aware of, the first few phases were adapted rather faithfully and the debatable part is mostly the second half of the show. From my viewpoint, I definitely felt like the beginning and generally the first half was also a lot more consistent in mood and pacing. You were slowly exploring Tanegashima, and over time the robot arc as well as the conspiracy arc made progress. At the end of each episode you felt like you moved forward a bit. No matter if it was just due to GunBuild being one step closer to completion, or new pieces were added to the Kimijima-puzzle. Characters were introduced, partially developed and felt relatable over time. Personally I was surprisingly satisfied with the direction, and I didn’t feel like the story was unnecessarily rushed (as far as I’m allowed to say that for a VN-adaption, that is).
This however changed in the second half. The more the story progressed, the more the backing mystery took over the plot and finally lead to several “character focused” episodes. Those focus on Junna, Frau and finally <Mystery Girl #1>, and while they give those characters some vital background information, they also throw you out of the momentum a bit. Suddenly you feel like GunBuild isn’t even important anymore, and even though as substitute the committee lore is picked up in a lot more detail, these episodes felt like shoehorned-in character routes.
On the other hand it’s also unfair to not give the anime credit here, because in my opinion some of those were directed quite well. While the first one (Junna) might still count as filler, it’s safe say <Mystery Girl #1>’s one was quite good and especially the 1 ½ episodes focusing on Frau were probably one of the best parts of the anime.
Her character is given some more serious treatment here, which came rather surprisingly. While her personality was somewhat entertaining, she was mostly degraded as necessary evil up until this point. However, the show manages to actually make you care about her, which also happens in a rather sincere and faithful manner. This even comes along with apparent character development, and felt like it should render Frau a bit more relatable. Unfortunately the aftermath only kept on throughout the following episode, and afterwards Frau was very quickly pushed out of focus again. I really wished for her to stay more relevant personally.
Kai – but who is he actually?
Another legitimate point of criticism is particularly Kai’s characterization. While the Visual Novel might have been able to express his thoughts as well, we lack those in the anime. The result is more often than not still an empty shell, which makes him seem needlessly naive. Carelessly pushing unknown buttons, without wasting a single thought on the consequences is just one example. Other ones include the limited insight into Kai’s feelings for other characters, most notably for Aki. Particularly since Kai is the main character, such thoughts would make it easier to relate to him.
And finally let’s come to the obvious pitfalls each Visual Novel adaptation stumbles into: Completeness. There are several plot elements which are picked up only to remain either borderline, or totally, unexplained. While the two-cour adaption follows its core-events close enough for them to make sense, a lot of less important questions remain unexplained. The result of such a lack of information dumps leads to some events which seem quite ridiculous without being aware of any background information. The following will explain one of those with information given in the VN (according to ItsRigs)
Remember the suddenly ‘raining’ monopoles? The anime never explains where they come from. During the typhoon Kai slightly changed the position of the HAARP radar, as he was breaking of one of the metal bars. That ‘radar’ sent out radio-waves, creating monopoles in the ionosphere. Due to its sightly altered position the conditions for creating monopoles turned out to be more optimal
Also near the ending you might have a hard time understanding what exactly the shown technology is doing, because you’ll only learn about its observable effects. Also an explanation for that part the anime won’t clear up:
The N IV device essentially sends out the same radio waves which were already radiated back at the Anemone incident, and caused Kai to experience his slow motion effect. Information on how to create them was stored on the cartridge ejected from the EGI-System, so that’s why it is necessary to be plugged into N IV. Kai simply reacts to those waves, which again push his visual perception out of sync.