I've gotten significantly farther into Dark Souls than I had the last time I wrote about the game. After defeating the Bell Gargoyles, I've vanquished the Capra Demon and the Gaping Dragon, and the Moonlight Butterfly. I've made a few attempts at the Stray Demon (which is actually the first enemy you see in the game, and is a bonus boss that you can find when you return to the Undead Asylum - the whole area kind of being a hidden secret area as far as I know.)
What's kind of fascinating about Dark Souls is that it's one massive inter-connected world. With the exception of the Undead Asylum, every part of the world is all within one massive area - you could essentially tie a string off in one place and, if it were long enough, pull it to any other part of the game (as far as I know. I have heard about this "painted world" that I believe you get to later on.)
it's a game with very distinct environments, but it folds back on itself in ways that are actually quite brilliant. Though I believe you do get a teleportation device later on, most of the world is connected via shortcuts. If you play through to the end of an area, you can usually unlock a door or kick down a ladder to allow you to get back there far more easily. For example, almost immediately after getting to Lordran after beating the tutorial section, you'll head up through an aqueduct, only to find a locked gate. Far later (and I honestly don't really remember how I got to some of these places, like the lower Undead Burgh, the first time around, without the shortcut) you'll find yourself at the other end of that tunnel and be able to open up that gate. After a fairly long and difficult journey to get there, you'll now be able to get back and forth from the Lower Burgh and Firelink Shrine (the kind of main hub/home area) with ease (though you will have to go through a small group of undead many times over.)
Finding one of these shortcuts is perhaps the most relieving moment in the game. You'll often find yourself fighting through an unfamiliar area, expending most of your Estus Flasks and desperately trying to make it through without dying. Finding that shortcut that then takes you practically right back to Firelink Shrine suddenly makes you feel safe - you pop into the Shrine, rest at that bonfire, and you know that when you go back in, you'll be able to get back out without too much trouble. It lets you decide whether you want to keep pushing forward or maybe turn back and try something else.
In a lot of ways, this gating system feels similar to Metroid, albeit a bit simpler (which is fine, because Dark Souls does not need to be more complex.) Rather than getting special weapons and tools that work in certain ways, you're usually just activating elevators or opening locked gates. But there is still this sense that you're gradually unlocking the whole game world.
There are some places, though, that aren't blocked off so much by locked gates and such, and more just really hard enemies. As far as I can tell, there's nothing stopping you from wandering into the New Londo Ruins when you first get to Lordran. But the enemies there are so strong (and I think require you to either be cursed or have a cursed weapon or an item that makes it seem as if you're cursed) that you'd be a fool to try to make it through there.
This system does require you to remember a lot about the structure of the map, or at least the paths through it. Still, I've found myself seriously shocked by some of these revelations - I was wandering through a dark, forested area and found a door that opened to a key I had, only to discover that I was at the bottom of a tower I had previously climbed up in order to fight the very first official boss in Lordran, the Taurus Demon - which I had thought was far, far away. I'm beginning to suspect that the layout of the game world is far more vertical than I had previously thought. It's amazing how well it all fits together.