cogadh: Prince of Persia Collection
GOG can only release what the publishers give them, so if Ubisoft only gave them SoT, that's what they released (though to be honest, I'm not sure Ubi has the rights to the earlier games).
- a CD with the two first games - was released in 2011 by Ubisoft, so they has the rights for publishing it. There was also two remakes for Android made by Ubisoft: Prince of Persia: Classic
and The Shadow and the Flame
I think I read some years ago that Jordan Mechner has the rights for the title, but Ubisoft bought the rights for publishing it from Broderbund, so Mechner can only release the games under Ubisoft label. At the same time, if Ubisoft want to make a new Prince of Persia
, they need Jordan Mechner permission and has to pay him the copyright..
I think that's the reason Ubisoft does not make new games for the franchise: they might rather release new Assassin's Creed
since it fills the niche of parkour-action games and do not need to pay the copyrights to the creator
As for Jordan Mecher, I don't think he is into game design anymore. His last work was a graphic novel named Templar
released in 2013.