Fighting against the True Final Boss (at the time before Update 2) Scott Cawthon is basically this, and it's all backed up with an amazing theme. Is it a bit scary because of the concept? Yes. Still awesome because of it? Yeah.
In Update 2, being able to finally kill Chica's Magic Rainbow is an amazing moment in of itself because it's not only a really hard boss that's under a time limit, but it's a huge payback after the endless taunting the rainbow gave you in its minigame.
Meta Example: The fact that FNaF World is re-released as freeware after the game didnt do so well on Steam. That alone is an amazing moment not just for the fans, but for Scott himself as he responded to the backlash the game got in a really unexpected way. Even the most adamant haters of the series showed some serious respect for Scott's decision. The new updates also helped and gave the game a much better reception than it did before.