Giant mode is the full board: 36 words and 9 hidden groups at once. At this size you cannot hold every possibility in your head, so solvers tend to work outward from the one group they are certain of and let the grid thin itself out. No daily limit, no waiting — hit "New Puzzle" the moment you finish and go again.
The rules are simple - the puzzle is anything but.
These habits separate the veterans from the newcomers.