To dream of playing darts represents your attempt to be "perfecter" or get something right more than someone else. Not wanting someone else proving themselves before you do. A competitive moment in your life where losing isn't an option.
It may also reflect your attempt to practice being perfect at something or get something right all the time.
Example: A young girl dreamed of fire darts that didn't work when she used them and they fell to the ground. She then cried. In waking life she had a speech impediment that her grandmother made fun of. The fire darts that didn't work may have reflected her frustrated vain attempt to speak perfect.