Alternate closures in Chrono Trigger ranged vastly from a cat filled parade in Crono’s honor to everyone turning into reptites. In addition to new dungeons and a monster arena, there is a brand new ending to find in the DS version of Chrono Trigger. Details about the ending have obviously not been announced aside from a two screenshots like this one of Marle, Frog, and Crono staring at a time gate.
Chrono Trigger also has a number of database features, some that fans will get a kick out of. You can watch a collection of animated movies, presumably those from the PSX port, in the movie theater, listen to tunes in the music library, look up monster data, and discover missing treasure chests with the treasure chest map mode.
Images courtesy of Square Enix / Famitsu.