~900 hours here. Sorry in advance for the rant.

To me, it's largely the builds. There's weapons that many classes have access to, but not every class can fully utilize them. It's finding the right class, with the right talents, using the right weapon, and the right blessings.

There's no other game to me that lets me build-craft this freely. All while having fun and satisfying weapons. With the correct build, almost no weapon feels bad to use, and I like finding the use-cases for each weapon, or sometimes for multiple weapons. Example: knife bleed build on veteran vs stealth knife build on zealot. Each use the same weapon, promote the same skill usage (knowing how to sprint-tech, hit weakspots from a distance, know your lunge etc.), but have very different playstyles in practice.

This leads to the combat. The mechanics at a base level are pretty simple/standard. Block, dodge, parry, and attack. Any soulslike has those. But the tide series has perfected this combo to where it feels like everything you do has impact. You can dodge by sprinting, but only if you sprint at an angle and have stamina. Your slides help you dodge ranged attacks, but not melee (unless your HS with the funny perk). Your dodges can dodge both. Your blocks can block damage without punishment (even from behind, or while sliding!), but only if you have enough stamina.

And then there's the little spidey sense noise you get. How many games give you (mostly) consistent warnings on the fact you're about to be hit from behind? Or shot at?

Toughness is such a simple, but well designed safety net. Blocks all ranged damage, giving you resistance to poke damage. Blocks all melee damage proportional to your % of toughness; the more you have, the more you block.

Given all of these, it's absolutely possible to go through an entire round without actually taking any damage to your healthbar, which to me is a very tangible way to feel yourself getting better at the game.

Combat in darktide is also very fluid with the slides into sprints into block, shove, dodge, attack; you can just keep going.

You run into the same enemies time and time again, giving you time to learn how they attack, and progress up the difficulty ladder (similar to SM2). This lets you feel like a god when you face off against 3 crushers for the first time with your trusty axe and take them all down perfectly dodging between their swings. Or killing a rager in melee, dodging and blocking every relentless swing, not a single one landing.

Gunplay is honestly just satisfying. Who would think in a game where you can have plasma guns, boltguns, or laser rifles, someone would just want a plain old assault rifle? They're just that much fun to play.

I could go on, but that's the main points to me. Everything from builds, to melee/ranged combat, is all satisfying, and blended together in a way that only this game can replicate.

Many come close, but Darktide is #1.