They are awful. Here's why.
This is the endgame section and I understand wanting to make changes in difficulty and even in tone. But the Deep Caverns tries to make too many simultaneous changes that when combined only increase tedium and frustration instead of being a pleasing and natural challenge. Here is everything it throws at us at once:
1. Vastly harder enemies. Makes sense for an endgame area, yes. But the resistances on some of these things are simply absurd. 75% Mechanical resist, trap immunity, stun immunity, worms that regen. Strategies that served you for the entirety of the game will now be useless in many fights, and there are fights everywhere, because
2. Endless respawns. Bots inside the power plant, Burrowers outside it, regrowing spore turrets, Tchortlings forever, and god forbid you're hostile to the Faceless. The enemies are endless, and your ability to kill them is not, because
3. Limited supplies. Regular ammo is plentiful, but regular ammo is not a sufficient match for what's thrown at you, because of enemy resistances. If you didn't bring your own armor-piercing rounds, batteries, high-end explosives, traps, special bolts, and chemical ammo, the warehouses will not help you. You can have all the regular bullets in the world and it won't do you any good against most of the enemies down here. It is entirely possible to find yourself in a situation where you cannot trade with either the Tchortists or the Faceless, and god help you trying to buy what you need from Leo. Speaking of allies,
4. You are blind, lost, and alone. Six gives you the worst "directions" in the world, and then you're dropped in the middle of a maze with no clear idea of where to go or what to do. This would ordinarily be an exciting opportunity for exploration! Except now...
5. You are punished for exploration instead of rewarded. Eye of Tchort punishes you for taking your time to explore and find out what you need to do and where you need to go. This is possibly the worst of all, because *exploration* is the heart and soul of the game up to this point. Now, you are forced to do it and punished for it at the same time. You will constantly need to backtrack and retrace your steps, whether it's to reroute the power or simply because you're lost, but every time you do, you meet more respawning enemies stealing your precious, dwindling, non-renewable resources from you. Exploration is now a tedious and frustrating chore instead of a joy. It feels like a slap in the face.
You can do any one or two of these things in an endgame area, maybe you can even do three of them. But you cannot do ALL of them at once and expect the player to enjoy herself.
***
The game is finished, and I doubt we will be seeing MAJOR changes to the Deep Caverns. But there have to be some small things that can be done to make this area less tedious, frustrating, and generally awful. Here are my suggestions.
--MAKE SIX HINT ABOUT LEO. Leo is the only guaranteed source of information the player has available, but he's hidden away in a corner behind a bunch of enemies, far from where the player starts, and hidden inside a locker. You might never find him on your own. Right now Six only tells the player to check out the Faceless and the mushroom forest. I get that you don't want Six to be Mr. Exposition, but adding the ability to simply ask "are there any other people down here?" and having him say he's seen an old man around to the northeast, or something like that, would be a tremendously bigger help than telling the player to go get lost in the mushroom forest.
--STOP LEO FROM LYING ABOUT THE MUSHROOM FOREST. He specifically tells you NOT to stand around in the spores, when that is EXACTLY what you need to do to progress! He also mentions he "ended up somewhere else," but unless you already know what needs to happen here, that is NOT what the player will focus on; they will focus on avoiding the danger he warned them about. Have him say something like "Those spores do strange things" instead of explicitly "Don't stand in the spores," and/or have him say MORE about the strange place he ended up, if you want his advice to helpful instead of misleading.
--STOP THE POWER PLANT BURROWERS FROM RESPAWNING. Burrowers are trash mobs. They are neither interesting nor challenging to fight like they were at level 6. The player will need to revisit the power plant probably numerous times as they figure out what the hell they are doing. Do not make us waste precious resources on trash mobs to do it. This is ridiculous:
http://steamcommunity.com/sharedfiles/filedetails/?id=593815743--or: JUST LET ME REROUTE POWER TO EVERYTHING AT ONCE. No more boring, annoying backtracking in the first place. Problem solved. Having to return here to reroute power adds nothing but frustration.
--SERIOUSLY RECONSIDER ENEMY RESISTANCES. 75-90% mechanical resist is simply absurd and makes fights into a tedious slog when you have limited resources. When you are without the ability to shop for things to adapt to new combat strategies, and you don't even really know where you're going or how much more combat you have to plan and ration for, this is not a fun challenge, it is just torture. You've suddenly taken us from an RPG to a survival horror game. That's not a fun surprise. You can either give us a better and more reliable ability to buy things, or you can give us enemies that don't eat bullets for breakfast lunch and dinner. Since I doubt you want to change interactions with the Deep Cavern factions too much, I suggest you make the enemies more reasonable.
--CONSIDERABLY REDUCE THE DURATION OF EYE OF TCHORT. Hiding in a hole is not compelling gameplay. Making me do it for fifty seconds while this debuff wears off is simply insulting.
--LET ME READ THE DAMN MUTAGEN SCANNER WITHOUT STACKING EYE OF TCHORT. I think someone else already suggested this. Allow me to repeat their request to stop the counter while the player is reading. Constantly having to stop reading to go hide in a hole adds nothing but tedium and annoyance.
I think these suggestions are reasonably simple and they would go a long way to removing the joyless slog from the Deep Caverns without removing legitimate challenge. Please consider it, Styg; this horrible place is currently not a fitting end to this wonderful game, and I know I'm not the only one who thinks so.