Antonyms for the word "anti-climactic" are:
1. Climactic: The event is building towards an exciting and thrilling climax, rather than a dull and disappointing end.
2. Surprising: The outcome of the event is unsuspected and unexpected, which leads to an exciting and thrilling experience.
3. Fulfilling: The event meets all the expectations and satisfies the audience, instead of leaving them disappointed and unfulfilled.
4. Satisfying: The event brings a sense of satisfaction and achievement, rather than being underwhelming and unsatisfying.