Typically, for me to consider a day 1 full price (or close to it) purchase of a full price game, it must fit into one of these two categories:
* A SaGa-like (this includes actual SaGa games, with the exception of Final Fantasy Legend 3)
* A DRPG (though I may require it to allow character and party customization)
Interestingly, NISA has put one game of each category on GOG; The Alliance Alive (a SaGa-like, though it's structured more like a traditional JRPG, but it does have SaGa-like character growth), and Saviors of Sapphire Wings/Stranger of Sword City Revisited.
Edit: There is the requirement that the game must be DRM-free, and on a platform where DRM is not the norm (and, in particular, must not be on a platform that explicitly supports/encourages DRM).
Buried In Time: Chrono Trigger 2 - The Dream Team reassembles to make a direct sequel to the original game.
In a way, Chrono Cross *is* a sequel to Chrono Trigger, though one could say it takes place in a different dimension without contradicting anything in either game. (Perhaps you want a sequel that takes place in a dimension where Chrono Cross didn't happen?)
(Worth noting; the added content in Chrono Trigger DS does not contradict the idea of Chrono Cross taking place in a different dimension. Remember, to see the tie-in to Chrono Cross's plot, you have to go through an area called the Dimensional Vortex, and it's quite reasonable to conclude that, once you reach the other end, you aren't in the same dimension anymore.)