The rules of chess are strict, and there are still more possible games than atoms in the universe.

Constraints do not shrink what is possible, they usually organize it. Six piece types with fixed moves produce a game nobody has come close to exhausting, because the rules are what make combination meaningful in the first place; with no rules there is nothing to combine. People treat limits as the enemy of creativity. Most of the time the limits are what make the creativity legible.

If you are stuck on something open ended, add a restriction on purpose. One color, two minutes, no dialogue, only what is in the room. It feels like handicapping yourself and it usually produces more ideas than the blank page did.