That's Fallout 3, and what you can't know until you've played one of these games is how hard they make you work to earn that. Games are empowerment fantasies, and when you start out in that particular universe, you are a refugee hiding underground in a shelter. Eventually you find a dinky little pistol that has like four bullets in it (in a universe full of bad guys who laugh off bullet wounds). In other games, you'll start out as a child with a wooden sword.
For hours you scurry around in fear, powerless. You die, you hide, you scrape for every little upgrade. And then, finally, you get the Game-Changing Weapon. Depending on the game, it might be a gun, or a spell, or a special ability. Whatever it is, it's laughably overpowered, beautiful to watch in action and incredibly satisfying when you unleash it on the same bad guys who tormented you in the early days.
In the Final Fantasy series, they have the Ultima spell:
Yes, that's a wild animal getting vaporized in a planet-sized explosion. But you have to put that ridiculous sequence in context. You've been charged with saving the world. You'll have some stupid freaking monster sitting there between you and your goal. Maybe it's one that has eaten you and your teammates alive a dozen times ...
... but now you have Ultima, a spell that casts down a pillar of holy light from the very heavens: