An old Squaresoft title, long thought to have been canceled, has been found and preserved online for anyone who wants to play it. The game in question is 3156 Coro Coro, which was developed by Hiromichi Tanaka, who would go on to produce Square titles like Secret of Mana and Xenogears, for the PC-8800 series, a line of home computers released in Japan by Nacon in 1981.
Chris Kohler, writing for video game preservation website Gaming Alexandria, relays the story of how the game was found. The game's existence had been known for a long time, but it was usually listed as a canceled PC-88 game, until Kohler stumbled across a Japanese website that said it had been created for the October 1985 Program Olympics in LOGiN Magazine, a Japanese magazine that ran for a few years in the '80s before spinning off Famitsu.
It turned out, as part of its preservation work, Gaming Alexandria was uploading hi-res scans of LOGiN Magazine, and had archived that issue only a few weeks before. 3156 Coro Coro had, in fact, been released in this issue as a type-in program, meaning its entire source code was printed in the back of the magazine, and users would have to enter it all themselves and save it to a cassette tape if they wanted to play the game. 3156 Coro Coro was a particularly large game for the time at 40K of machine code. (Here is an example of one of the sixteen pages of hexadecimal code users were expected to input.)
All that effort isn't necessary in 2022, however. Gaming Alexandria founder Dustin Hubbard was able to cleanly extract the text from the scan, and even built a tape file format that's compatible with PC-88 emulators.
As for what 3156 Coro Coro actually is, it's a puzzle dice game, though it seems to have a larger emphasis on strategy over luck than most dice games. Players need to guide a die to a certain point on a grid in a certain number of moves. However, each space on the grid has several numbers on it, and the number on the bottom of the die cannot match the number on that square of the grid. So, if the square to your right has a 1, 3, and 5 on it, then you can only move to the right if that will make a 2, 4, or 6 face down. There are only three levels but Kohler says they are "pretty difficult" and he hasn't managed to beat the last one yet.
For a link to the tape image, instructions on how to get it running, and a recommendation for a PC-8800 emulator, you can check out the Gaming Alexandria article here.