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How these two elements could have come together remains unknown, but it was likely part of a reference to Ico's voice actor, Kazuhiro Shindō, and his prior role as 'Boku' in the first installment of the Boku no Natsuyasumi series.
Boku no Natsuyasumi had an extensive bug-catching and beetle fighting system. These features reappearing in ICO were potentially meant to be an elaborate reference, playing on the idea that Kazuhiro Shindō is once again voicing a young boy, who might refer to himself with the first-person pronoun 'boku', if he were to speak Japanese.
This video displays both the Japanese Rhinoceros Beetle and the wireframe of the unused Insect Net weapon:
https://www.youtube.com/watch?v=qkyGF-8bSsg
The credits for both ICO and Boku No Nastuyasumi show that both protagonists' voice actors have the same name. I have highlighted both names in a combined screenshot attached.
ICO credits:
https://www.youtube.com/watch?v=PqL1OIvveN8#t=240
Boku no Natsuyasumi credits:
https://www.youtube.com/watch?v=gu3bOtajQLs#t=41058
Additionally, Kazuhiro Shindō's Japanese Wikipedia article confirms his video game roles. Providing evidence that he really was the voice of both characters:
https://ja.wikipedia.org/wiki/進藤一宏#ゲーム
https://www.youtube.com/watch?v=qkyGF-8bSsg
The credits for both ICO and Boku No Nastuyasumi show that both protagonists' voice actors have the same name. I have highlighted both names in a combined screenshot attached.
ICO credits:
https://www.youtube.com/watch?v=PqL1OIvveN8#t=240
Boku no Natsuyasumi credits:
https://www.youtube.com/watch?v=gu3bOtajQLs#t=41058
Additionally, Kazuhiro Shindō's Japanese Wikipedia article confirms his video game roles. Providing evidence that he really was the voice of both characters:
https://ja.wikipedia.org/wiki/進藤一宏#ゲーム
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This is somewhat corroborated by the movie's presence on Ueda's shelf, which is shown in this same art book.
Hilda's character traits and arc are very different from that of Yorda, but her dynamic between the valiant Horus and the ice devil Grunwald seemed to serve as a heavy inspiration for ICO's narrative.
Shinwa wo Tsumugu art book - The quote can be found on page 45 of 52 in this PDF, in the section labelled with the number 4. I have attached a picture as well, both in Japanese as there is no official translation:
https://mega.nz/file/RwdjGBJQ#7cI7fMueAwI24tYYjQZI4_LKBHCYPb_aPEqgTWykr9k
Ueda's shelf is on page 37 of 52 and 'Horus' can be seen near where the movies stop and the Xbox titles begin.
https://mega.nz/file/RwdjGBJQ#7cI7fMueAwI24tYYjQZI4_LKBHCYPb_aPEqgTWykr9k
Ueda's shelf is on page 37 of 52 and 'Horus' can be seen near where the movies stop and the Xbox titles begin.
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Though there was no particular base behind the languages, Ueda equates Ico's spoken language to Chinese and Yorda's language to French.
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In response to criticisms that Ico's combat was too simplistic, Fumito Ueda stated:
"Ico's battles were just one way to create situations in which the player protects the girl. So I thought that the battles should not require the player to be very skilled."
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There is a novelization of the game called Ico: Castle in the Mist by Japanese author Miyabe Miyuki, written out of appreciation for the game. The novel provides backstory in an alternate perspective for the characters not featured in the game, and Miyuki's personal interpretation of the story. The novel is thus considered to be non-canonical.
Miyuki thanks the games producers and creators in the closing comments for allowing her the creative freedom with the story and the use of the same cover art as the game.
Miyuki thanks the games producers and creators in the closing comments for allowing her the creative freedom with the story and the use of the same cover art as the game.
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To help the game's themes, narrative, and puzzle elements stand out, the team implemented a method called "Design by Subtraction", in which they removed elements which were superfluous or interfered with the game's core concepts.
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Early footage shows Yorda was originally going to have horns and Ico was not. However the footage portrays Ico with horns during different segments of the clip.
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Ueda's main inspiration for Ico was Another World, which used cinematic cutscenes and lacked any head-up display elements as to play like a movie. It also featured an emotional connection between two characters, despite the use of minimal dialog. Ueda also cited Lemmings, Flashback and the original Prince of Persia games as influences.
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In the game's demo, the player had the option of letting go of Yorda's hand after catching her when she jumps across the bridge. This feature was removed completely in the final release.
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After two years of development, the team ran into limitations on the PlayStation hardware and faced terminating the project altogether. However, the team decided to remain true to Ueda's vision, and shifted the project's development to the PlayStation 2.
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Ueda wanted to make sure that a translation of Yorda speech was not included, in order to emphasize the language barrier between Ico and Yorda, and strengthen the "holding hands" concept of the game.
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The development team was able to provide planned box art by Fumito Ueda's and additional features such as a two-player mode in time for the game's Japanese and PAL releases, but these weren't ready in time for Sony's planned North American release date.
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