Full disclosure: I was a patron for this game for awhile, so I've followed it through a lot of it's development.
Did you like the idea of MadoDevs previous game, but you weren't really comfortable seeing Madoka characters get sexually tortured? Are you more about bondage and sexy outfits than you are about sex? Did you play Darkest Dungeons (and even Lewdest Dungeons) and think "This could use more sexualized anime girls? If so, you've found your game.
Ero Dungeons is a game in the vein of Darkest Dungeons (Ed: I have not played Darkest Dungeons) where you are a guildmaster, hiring and directing girls to explore dungeons, largely because making girls explore dungeons is kinda fun. These dungeons can vary in theming and fetishes, and generally also involve getting equipped with cursed item sets and parasites. (If you played Ero Witches and haven't figured out MadoDev loves cursed items and parasites, uh, they do. A lot. And they write it well!) On the flip side, you also receive levels and gear for winning fights, clearing dungeons, and completing challenges, allowing you to arm your girls to take on bigger challenges. All the while, you're collecting resources to expand your base of operations and unlock upgrades for the entire team.
The gameplay is more or less simple turn-based combat, with turn order decided by agility and able to be manipulated through certain abilities. The overworld map also contains Curios, events that can have wonderful or terrible effects for your team of girls. At the onset, it seems pretty clear you want to avoid cursed items and collect rare items, but the further you go into gameplay, the more you realize that cursed items and classes can have tremendous benefit if utilized well, both in combat and working jobs around the base.
This is one of Ero Dungeons hallmarks; it's a fullfledged game, mechanically, and very quickly turns up the difficulty once you're familiar with the gameplay loop. Your girls can be kidnapped if they take enough damage in battle, and it's very much expected for this to happen. Kidnapped girls can be rescued, but the mission starts out extremely hard; as time goes on, it gets easier, but the more cursed items will be placed on your girl, forcing her into a corrupted class. This can lead to frustration from bad runs, as a girl who you poured a lot of time and effort into can be swept away, and by the time she's rescued she's been forced into a very difficult to change cursed class. The game does give you an option to make this easier, but it comes fairly late in your base development and relies on more difficult to obtain currency than most other systems. As you go into higher and higher dungeons, the game forces you to be more clever with your use of abilties in both combat and the field, with the boss battles being just as much a puzzle as they are a fight.
The ero content here is largely nonsexual. Many enemies have both physical and sexual attacks; while arousal doesn't damage your character it can very easily handicap them enough for the physical attacks to bring them down. On top of that, it feeds into crests that debuff the girls against certain enemies and mechanics. The physical attakcs, in addition to damaging your girls, can also damage their clothing, and enemies will gleefully leap on any unfilled equipment slots with their own cursed equipment. While there is some penetrative sex, these debuffs and cursed gear are the driving force of the ero side of the game.
Between the difficulty of the game and the specific focus of fetishes here, Ero Dungeons is certainly not for everyone. If you're looking to see girls get pinned down and raped in various ways, you're better off finding another game to play. The sprites, even, don't lend themselves well to sexual fantasizing. All of this means that Ero Dungeons leans on the writing and implications of gameplay more than it does open sexual content, and for what it's worth, both of these are masterfully executed. It appeals to a very certain niche, and the design certainly isn't perfect, but if you're like me and like binding and bad status games, this is a pretty fun game to spend time with. If you like it enough to really spend some time with it, there's even a robust modding community!
Finally, in a purely selfish move, I have to knock ~half a star off for the soundtrack. I do not like the music here, it doesn't really feel like it matches the game, and it's one of those soundtracks that just kind of grates after awhile of listening to it. I'll take another half star off just for how sadistic it can be at times (and because I can't do partial stars), but consider my review a very low four star.