What you see up there is a video from youtuber DeadSotc which he lauds as a tribute to his favorite weapon in Fallout, the sledgehammer. Specifically, the Super Sledge. The video is exactly what you imagine it would be; a compilation of a player going around wrecking enemies with a sledgehammer.
I don't have a capture card (or really an understanding of let's play making) so I can't show footage of how I'm doing my first Fallout 4 playthrough, but this video is pretty close to how it's going. Except I use a heavy sledgehammer, and only a heated super sledge when I need some bonus energy damage.
It makes for a weirdly satisfying experience, though it does make me question my moral decision making more than a gun would, I think.
In addition to my strength being high (I think base 8, then power armor bonus usually) I took 4 levels in the Big Leagues perk, meaning I do +80% damage with melee weapons and get to hit everyone in front of me instead of just the one.
So I go around obliterating enemies. In the beginning, it was just a rush when I made a raider explode into a million bloody parts with my razor-lined bat. It was exhilarating.
But then you get a couple dozen levels stronger, better equipped, and the narrative stakes get higher. The bat becomes a sledgehammer, then a heavy sledgehammer. Blood is a nigh-omnipresent paint job on your armor, the head of the hammer.
Now the bone-crushing exhilaration has faded, as yet another body crumples at your feet. The brunt of your hammer has killed Mirelurk Kings and Queens, Deathclaws and Super Mutants.
With the body count piling behind you, they all begin to blur into a legacy of blood-soaked fury. There is nothing calculated in this. Were you gunning them down, you could probably put some distance between the carnage and yourself. But you don't. You see the look in every eye as the life explodes out of them.
You look at Dogmeat, and think of all the wild mongrels and attack dogs that have had their skulls crushed under the weight of your power. You look at Dogmeat and wonder, can you love him? Can you see him as somehow different from the hordes that have seen the force of your anger?
How many times, in your bloodrage, have you accidentally knocked him out of the fight? Does he remember the way you killed the small swarm of Deathclaws? Does it stay with him, your wicked, triumphant laughter?
It stays with you. It's in you, somewhere. You are this person. You have the capacity for this, and it makes you question yourself in your core.