https://itch.io/games/tag-demake/tag-pico-8
Some of these projects like Alone in the Dark and UnduneII are incredible.
The forum post for UnduneII has lots of info on it's creation: https://www.lexaloffle.com/bbs/?tid=47155
I am not sure but I think that the developer changed the game title and the platform.
Correct, the wiki page you linked actually mentions this:
> It was developed in 2002, and was due to be released in Fall of 2005. It was never released, and instead it was replaced with a brand new game, Retro City Rampage.
Here is the game in question:
Retro City Rampage did actually get "retro system" releases -- for DOS and Windows 3.1.
(There was also ‘Driver’ for GBC.)