Character Study. Create a single character. Don't bother about any narrative plot, timeline or events; just create a full person out of your words. Describe its appearance, likes, dislikes, behavior, etc. Make us, the readers, fall in love with this person, or absolutely hate them, or pity them, or want to slap some sense into them, or to snuggle them and make them feel safe. Make us feel something for them. Write it as either a Narative or Poem.
Utopia. Create your idea of a best possible society- realize that nothing is perfect, so account for human nature. What is the government like? How is it structured? What is the economic system like? How are laws created and enforced? How rich are the rich, how poor are the poor? How are the sick and elderly treated? How does it handle foreign relations- both with friendly nations and with aggressive nations? How does it deal with religious diversity, language diversity, sexual diversity, diversity of families, etc. You can write it in naritive form with a central character, or as an essay.
Try to be as detailed as possible. Think about questions a critic might ask, and answer them pre-emptively.