Premises you can begin writing from immediately, the museum of unfinished things, rather than the theme of loss.
Asked for a theme, most generators produce a noun: loss, betrayal, redemption. Those are what a story turns out to be about, discovered somewhere around the second draft. They are not something you can begin writing from. Every entry here is a premise instead: the museum of unfinished things, letters that arrive fifty years late, a town where everyone dreams the same dream. A premise contains a situation and an implied question, and a question is what a first scene answers. The abstract theme will emerge on its own once the story exists.
Under a time limit the premise matters more than usual, because you cannot afford the days of circling that an open brief produces. A concrete premise gives you a mechanic or a scene immediately, a town sharing one dream suggests both a puzzle structure and an opening image. The standard advice for jams applies here too: take the first premise that produces a reaction rather than drawing repeatedly for a better one, because the search itself is the expensive part and the constraint is what you are actually buying.
Because a word like loss is what a story turns out to be about, not something you can start writing from. A premise contains a situation and a question.
Yes, and the collision often produces something better than either alone. Draw several and look for two that create tension together.
That is one of the main uses. Take the first one that produces a reaction rather than drawing repeatedly. The searching is the expensive part.