General Antonyms:
* Novelty: Something new and exciting.
* Spontaneity: Doing things without planning or preparation.
* Adventure: An exciting and unusual experience.
* Chaos: Complete disorder and confusion.
* Unpredictability: The quality of being impossible to predict.
More specific antonyms depending on context:
* Change: A variation or departure from the usual.
* Excitement: A feeling of great happiness and eagerness.
* Improvisation: Doing something without planning, often in a creative way.
* Innovation: The introduction of new ideas or methods.
The best antonym will depend on the specific context in which you are using the word "routine."