4D Mode is a difficulty setting exclusive to Star Ocean: Till the End of Time. Comparable to Chaos Mode in Star Ocean: The Last Hope, 4D Mode is the hardest difficulty level in the game, harder than even Universe, due to enemies' stats receiving a larger bonus than in Universe Mode. On average, all enemy HP is 1.8 times greater than on Galaxy difficulty with some 2.0 times greater. At this level it isn't that far to call the AI partners nothing more then cattle. There are several glitches in the 4D mode of Star Ocean:Till the End of Time, leding some players to consider Universe mode to be more difficult and a Universe mode + Gutsy Bunny to be the hardest mode in the game.
To obtain this difficulty level, the player must collect 195 out of 300 Battle Trophies. As in Universe Mode, there are certain Battle Trophies that can only be obtained in 4D Mode (i.e. defeat Luther or any of the post-game bosses in 4D mode under determined conditions regarding time or characters used).