Earlier today, Inti Creates held a Japanese holiday livestream, and during the stream, Inti Creates president Takuya Aizu and game designer Yoshihisa Tsuda casually let slip that a Mega Man ZX3 was once in development, going by the codename “ZXC.” As fans know, only two entries in the franchise were ever actually released — Mega Man ZX and Mega Man ZX Advent for Nintendo DS — and they were a Metroidvania-like take on Mega Man that still played in a Mega Man Zero-ish way. But the story evidently doesn’t end there, and at Rockman Corner, Sidier has provided a translation of the relevant stream segment discussing Mega Man ZX3 / ZXC.
In the stream, Aizu referenced how Tsuda had designed the mechanics (not the physical art) for the main character in Mega Man ZX3, revealing the game’s existence:
Aizu: Well, you know, Mr. Tsuda made ZX3‘s player character, right? He was working on the ZX3 player character and then brought what he had to Mega Man 9‘s player character. It was made in the middle of ZX3‘s development.
Tsuda: I-is it okay to talk about this topic? Is this a good idea?
Aizu: There is no such thing as a “ZX3” game! [laughing]
Aizu: Because the right name is ZX “C”!
Tsuda: Yes. I’m certain the project’s codename was “ZXC”.
Furthermore, a “Yabe,” presumably Makoto Yabe, also known as “KOU,” wrote “setting materials” for Mega Man ZX3 / ZXC. The phrasing of “made in the middle of ZX3‘s development” by Aizu makes it sound like the game progressed relatively far before ultimately being canceled by Capcom, presumably during the development of Mega Man 9. For reference, ZX Advent launched in 2007, and Mega Man 9 launched in 2008.
Tsuda joked that, if you want to complain about Mega Man ZX3 being canceled, you should talk to Capcom, but Aizu noted that anyone involved in the decision to cancel the game, including Keiji Inafune, is gone now. (Incidentally, Inafune is working directly with Inti Creates on Azure Striker Gunvolt 3 right now, so there is clearly no bad blood.)
As for why Inti Creates referred to the game as ZXC, it probably had to do with whatever subtitle was to be attached to the title, like how ZX Advent is sometimes referred to as ZXA. It’s anyone’s guess what the C might have stood for. (How about Carrots?) It’s a bummer that Mega Man ZX3 never saw the light of day considering how strong a game ZX Advent turned out to be, but insufficient sales of the first two games is likely the reason for the cancellation. At least you can play those two original games and all of the Zero series in Mega Man Zero/ZX Legacy Collection, which is excellent and currently on sale on the Switch eShop.