This isn't so much a gripe about difficulty of dungeon content as it is about a set of perceived issues with the design of dungeons. I've done some ant dungeons and beaver dungeons with my small but well off village and.... I have a few complaints and suggestions.
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First off, they come across as neat side "MMO-style" content, this is fine and has potential to be fun. But the difficulty padding simply being a constant onslaught of spawning enemies in rooms more often than not isn't really difficulty, but tedium, tedium which encourages cheesy mechanical wrote and repeat strats like making progression and running back to heal, kiting in a circle and spamming restorations before getting a few hits back in and repeating. Or simply zerging it with raw attribute and gear power and numbers over actually doing it when it's a relevant challenge. I'll break down the issues and list a solution to go with them so I'm constructive and not just a negative nancy.
1)Endlessly respawning fodder enemies aren't really fun. I would rather fight far tougher enemies with far more lethal attacks and risk VS reward that you put down -once- than a horde of nothing enemies that either tickle you fruitlessly or just beat you down through opening attrition. With little middle ground. From diablo's auto rezzing enemies onward in gaming history you'll be hard pressed to find anyone who enjoys this as a mechanic- Defending it as a challenge? Sure. ENJOYING it actively or calling it fun? Less so. It's irritating that there is no break or downtime at all to even have the liberty to check through containers and chests in some areas as a result too- It's just a constant rush rush rush with no time to even appreciate overcoming a room.
2)Keys are not that engaging from a gameplay perspective but more of a chore. Instead- having basic puzzles to solve ala zelda (IE: Lift this, put this there- Figure out what you need to do in the room, light all the torches in a pattern before they go out, Place these things in the right order, etc. Lots of things are possible even in the current engine.) and "mini bosses" as door progression blocks would be a more engaging from a gameplay angle than meticulously keeping track of identical unmarked keys until a run is finished. We have so many things we can do and interact with and ways to do things and dungeon content essentially ignores the possibilities as is.
3)Boss fights themselves are underwhelming. The ant queen is less terrifying than a common bear, the beaver king is more trivial than an angler.... There are no interesting or fun mechanics in place for these outside of just being stat tweaked basic mobs..
IE: The beaver king's room could have supports like a mine- and now and then in an attempt to deal with you he'll try to gnaw one down to bring some of the roof down on you like a cave in and you have to do something to interrupt it or it has a timed delay on it and you have to use salvage or wood to brace the supports back up mid fight. The ant queen could lay eggs that spawn additional enemies and you have to have a village-mate (Or yourself) on the ball to keep them culled before they hatch to keep from being overwhelmed by additional enemies instead of it just being a constant... These are just ideas- anything really besides just "Hit until it dies."
There is a lot possible in engine to spice up dungeon content and make it more approachable and desirable for people to do beyond "Just make rewards better." But also more challenging in the actual sense of the word. And I feel in it's current form it's more of a chore people endure and slog through to get a few items of note and then never touch it again until those specific items are needed again.
It's got so much potential to be fleshed out and fun but falls short in it's current incarnation.