So Dark Souls 1 then:
Technically the second game in the "souls" series, Dark Souls if the first game that took the series into popularity. The game took the formula from DEmon's Souls and place it into a more interconnected world and refined a lot of the mechanics from that game. Gone was the world tendancy, weapons and gear were much lower to break though they still had durability which needed repairing, weapon upgrading was much easier, and gone was the world tendancy as well as the half health punishment for death.
Dark Souls remained a difficult game while at the same time removing a lot of shit that was just bullshit from before. There was no reason to punish failure as harshly as the first game did so this ended up making Dark Souls 1 just accessable enough that it began to catch on.
Going from the Demon's Soul remake into Dark Souls 1 is a bit of a challenge due to how clunky the game feels to play compared to the more polished experiences of Elden Ring. It made adjusting to Dark Souls 1 a bit of a pain in the ass, however the slowness of everything made the challenge not so bad. People often praise the game for how interconnected the world is and how everything loops together, a feature that people claim doesn't happen in any other title. But really this is only half true. There are several sections that weave around each other like the Undead Settlement, but for the most part the game is more like Dark Souls 2 than people realize.
After the Undead Perish, the game's levels are pretty linear. Yes they do branch off of Firelink Shrine but they don't typically wind back around on themselves. Andor Londo kind of loops on itself, but not realy much. It's a big illuision that people remember about Dark Souls 1 because they likely spend so much time in Undead Burg during their first playthroughs that it just felt like the game is so interwoven, but that's not really the case outside a couple of shortcuts later.
While DS1 has less bullshit than DemS, it still has a fair share of it. The Toxic spitters as you climb down Undead Burg, though thankfully these dont respawn once you kill them which makes suciding them worth it. Curse is also a big fuck you mechanic which instantly kills you, then upon respawning you have half health, take more damage, and deal less damage. Getting rid of curse requires a special item or the creepy guy at the Belfrey tower just beyond the Gargoyle fight. This sucks because the enemies that inflect curse are way way way far away from the Belfrey tower and you'll likely encounter them way before getting the Lord Vessel which allows you to warp between bond fires. Making Curse unbelievably unfair.
Fairness is an interesting thing about these Souls games too, a lot of people use the phrase "tough but fair" when talking about the Souls difficulty and that is also not true and has never been true. Souls games fuck the player more often than not due to poor enemy design and/or placement, terribly punishing mechanics, and unexplained consequences. Demon's Souls gets harder the more you fail, unless you KNOW to play in soul form with 50% of your max health at all times. Dark Souls doesn't get harder for each death, but there are lots of bad enemy placements in and status afflictions that the player can't reasonably deal with resulting in unfair difficulty spikes.
All that being said, Dark Souls has a wonderful level variety and enemy variety until the late game where generic lava levels start to be the norm. And everything does feel very slow in this game compared to later titles by Fromsoft, which helps make these games retroactively easier. Though the later half of the game does feel rushed with lots of copy/pasted enemies, spammed bosses like Capra Demon and Taurus Demons, which makes the ending areas feel like you are just avoiding as much as possible before reaching bosses.
Getting to some areas and bosses can be a pain because a lot of it is very obtuse which I really don't understand why FromSoft has such a boner for this quest design. It's not challenging to give the player no information, it's not fun to miss zones or quests or not knowing you need a special ring equiped to fight the Four Kings. It's just bad design. And it makes me wonder if this studio is prone by some sort of laziness affliction because from this game onwards the later stages of every FromSoft game from here on out has a lazy back half that can feel really bad to play.
Dark Souls 1 is not my favorite, the clunky sluggish combat, obtuse mechanics, and lack luster back half leave this one just disappointing.