Shigesato Itoi (Mother), Shigeru Miyamoto (Mario, Zelda) and Tsunekazu Ishihara (Pokemon), all working on the same game? We should have known it would be too good to be true.
In 1997, Nintendo announced a game called Cabbage. It sounded weird (by 1997 standards, anyway), was headed for a weird console and had a (presumably working) title that made it sound like something a kid would normally avoid.
But what a team that was. Drawing on the experiences and expertise of the men designing it, Cabbage was essentially Nintendo's take on Tamagotchi, with players put in control of a creature (whose name was Cabbage) that they'd have to raise, feed and even carry around with them (more on that soon).
Designed for the Nintendo 64DD — an improved version of the N64, which used proprietary magnetic disks for added storage and which never made it to the West — Cabbage was going to make the most of the gear the 64DD had which the regular 64 did not.
The Nintendo 64DD: right idea, wrong time.
As Unseen 64 report (based on archived old stories about the game), Cabbage was intended to use the 64DD's internal clock (to keep the character and virtual world running even when the console was off), Game Boy connectivity (the creature could be transferred to the GB, tended to during the day then returned to the 64DD at night) and network functionality to visit other player's worlds.
There were also plans to release more content on "disks", which would include stuff like toys and play equipment for Cabbage.
Plans that came to nothing, of course, because the game was never released. It never even got far enough along for video or even screenshots to be released before it was cancelled. Why? In a 2006 interview with Japanese magazine Nintendo Dream, Miyamoto simply said "Itoi and Ishihara got busy" with other projects. The commercial failure of the N64DD (it only sold 15,000 units in Japan in its entire lifetime) didn't help, either.
We may never have seen Cabbage, let alone played it, but elements of its design lived on in other Nintendo projects. While Nintendo never officially drew a line, it's not hard to see the ideas first laid out in Cabbage turn up a few years later in Animal Crossing (which was first released in Japan on the N64), with its persistent towns and personal trinkets for the player.