I had a mind of my own to make a Gale of Darkness sequel many years ago. I still do and I still have all my very rudimentary documentation for it, but this was when I had no real idea how to make games, so it fell to the wayside. I always felt the Colosseum continuity needed a third game to round off the saga, and there was a perfect hook for it at the end of Gale of Darkness; Eldes and Greevil were arrested, but Ardos escaped and planned to revive Cipher one more time. This completely leaves it open for Ardos to restructure Cipher and terrorize Orre once more. However, it's kinda hard to follow up on making an ultra Shadow Pokemon like Lugia, both in and out of universe. The only next logical steps of threat progression are multiple Shadow Legendaries like Lugia, and/or Shadow Arceus as the game's ultimate Shadow Pokemon.
I had quite a few ideas in mind for places in this game, as well as what would be done where, but it was never enough to fully make it. I had always wanted to go back to it one day, but it feels extremely difficult without making it feel awkward.