I don't have an answer for why, but: here's the Steam Community page asking why it was delisted. No update from the developer or anyone in the know from the community, if you get an answer, I would recommend posting it there, as it's one of the places owners are likely to go for an answer.
From seeing other games that have been delisted, the two most common causes I've seen are review shenanigans or not owning the content within the game, such as when the license for music used in the game expires, or the game was built with assets the developer never owned. I am not accusing the developer or publisher of either, and there can be other causes, including the developer/publisher simply wishing to pull the game from Steam.
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*facepalm* Sorry, wasn't paying attention.
It is possible for games to be relisted, such as with Castle of Illusion, but that depends heavily on the reason for the delisting and what the developer/publisher can do about that. In this case, I see Fugazo has another game up on Steam (Committed: Mystery at Shady Pines - Premium Edition) with Fugazo listed as the publisher, rather than Viva Media, publisher for CA:FAK. It sounds like they've gone their separate ways and, speculation on my part, that could point to a dispute between the two. That's actually a good sign, compared to some of the things that can get a game delisted, as that would be something they could potentially work out between themselves.
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