The phrase "climactic moment" refers to the most intense or exciting part of a story, event, or performance. It is the point of highest tension or action that often leads to a resolution or conclusion. Full definition
It's probably the most climactic moment in any story that's ever been written. (relevantmagazine.com)
Instead of any sort of closure, the game simply ends after one of its most climactic moments, leaving any sort of resolution in a future sequel. (monstervine.com)
(After all, there aren't many board games to be seen after 15 minutes or so, though there is a very cute use of charades at a crucial climactic moment.) (vulture.com)