SECTION RANKING
There's something about Xenogears that I could never, fully, call their areas 'dungeons' or 'levels' but this is essentially a breakdown of how each area plays out; the good, the bad, and the ugly. None of this is a walkthrough, mind you, but there will be spoilers galore, so watch out. I am updating this as I replay Xenogears but also, I do have a little thing called A Job so it may take a while to go over everything as a whole.
PATH TO CITAN'S HOUSE I actually love this as an opening area, it's confined but small enough to let you stretch your legs on the platforming. There's actually a specific tree that allows you to goad a chicken out by stealing it's egg. This doesn't do much other than act as an out-of-battle status effect as the chicken continuously pecks at you, stealing your health as if you've been poisoned. I actually looked it up and a guide says that Citan's wife will cook it for you but, it mostly just seems like some extra flavor added into the world(we'll see a lot of that throughout this series). Don't forget to farm for Hobgob meat!! FOREST OUTSIDE LAHAN This is where you meet Elly which, if you're like me, you'll immediately get her and go "Oh! I should work to level her up as much as I can!" you don't really have to do this. She'll be gone in like ten minutes, tops, and she won't show up again as a party member for several hours. This is one of those parts of a game where they really take advantage of the terrain(even moreso than the last level) only to basically never do any of that shit ever again. I love ping-ponging between different areas of the battlefield but both of these areas set up a precedent that the rest of the game just never follows up on. Once you watch thirty minutes of cutscenes and Elly dumps you, you now have Citan. Oh joy! THE DESERT I actually really love when the world opens up from Lahan into just this long stretch of desert. Being confined to dirt paths and forests only to now feel the immense expanse of the world is enough to make you go "So I wonder what happens if I just start walking in one direction and keep going" in which your answer is "the game will punish you for that". This is a good opportunity to have Citan and Fei run circles around each other until they're beefed up enough to proceed the plot and take on the desert for realsies. Navigating the desert, itself, is a bit of a pain but it's also not really all that painful at all. Trust me, I've played Breath of Fire III, there's nothing worse than a terribly made desert level that's built to punish you for even dreaming of stepping up to it. In actuality, you just have to mess around for a bit, walk around in different directions, you'll be fine. Well, you'll be fine until the giant worm shows up and you're ripping your hair out going "how the fuck am I supposed to fight this thing if my attacks won't work on it!?" but that's just the Xenogears experience for you. THE PRISON SHIP Did not actually know until later that there are two paths to take when the damn thing goes under. Really the shortest section of Xenogears, only really worth mentioning due to how fucking bonkers it is. Feels like it's over before you get a chance to catch your breath. THE UNDERGROUND CAVERNS We now have Bart along for the ride! I actually always get a sense of panic when playing the earlier parts of Xenogears. Not pants-shittingly scared panic, just that the early sections really grab you by the pants and rush you along. Essentially, I just head straight for Balthazar's cave, no stopping, because that's where you can run to get your gears refreshed. After that, this is actually a pretty nice area to grind in. Put on some Slipknot, spin around in circles, fight a few horrifying fly-infected mechs, whatever. You have a very simple "push the button" puzzle to do in order to leave but, honestly, you'll be up against a number of enemies once you leave so it's best to just spend a few hours down here.