The Villain would begin by creating a dungeon and getting it approved. After this, they can start trying to find characters based on char-threads, or by PMing people they're interested in.
Villain's PM said:
(Hey, I saw your character Marie and thought she'd be great for a raunchy dungeon idea I had. I'll be posting the dungeon's start later today!)
This kind of a PM would be typical to help advertise a dungeon. By messaging Marie's player, the dungeon owner has gotten the Adventurer's attention, but not locked onto Marie as the only person who can enter.
Villain said:
(OOC Info: This dungeon is made for level 0 characters in a fantasy world, no teaming up. Magic is not heavily needed, but expect lots of Lewd/Naughty attacks. It's a small dungeon, and girls should expect lots of messy rape and a bit of bestiality. I prefer 3 or so posts a day, and post size of around a paragraph.)
It was an old wives' tale, circulated for years as a joke against the waitresses in their skimpy outfits. As if such a thing could be real, magical flask that any waitress pouring from it would never be harassed or groped, and best of all, it was in a cave nearby! Imagine! Waitresses from all of the local taverns and gambling joints were mostly skeptical... but every so often, one of them couldn't help but try to find it...
Those girls trying to find the dungeon will often be seen roaming the forest just outside of town to the north, wary of goblins, orcs, and other nasty things, but too embarrassed about actually following up on such a rumor to ever ask for help as they stumble alone into the night to search.
This post has all important OOC info in it, level, setting, suggestions of characters to enter, including how many can enter and what stat focus they should have, plus fetishes and post size/frequency.
From an IC side, it's a bit custom tailored to Marie (from my Adventurer example), but that's fine since other people may take interest too, even if Marie's player doesn't.
Adventurer's trying to get in should take a few hints here, like wandering around at night, and use this to "lure" the dungeon into taking them.
Marie's Player said:
(Spoiler Tag with char sheet) (Not present since this is just an example.)
Marie cried out as she felt the sting of another bush against her cheek, whimpering in the darkness, she'd torn her top a bit and knew she'd have to sew it before tomorrow, otherwise she'd be having hands on her tits all night...
Not that she didn't normally, but there was a big difference between groped through one's top compared to having those drunkards' hands slipping into your clothes to cop a feel and pinch at your sensitive nipples.
She huffed, letting her guard down again, and once more her torn top slipped loose, standing bare breasted in the middle of the forest, barely able to see anything, and about to scream in frustration.
If she didn't find the dungeon soon, she was going to give up.
This is a typical "trying to enter the dungeon" opening post. It shows that Marie's player is interested and read the Villain's post. She's wandering around, as expected, at night. And to add flaire and encouragement, she's already hinted at her outfit being damaged and being at her wit's end.
The character sheet at the start is for a reminder to the Villain about the character ready to enter the dungeon. At this point, the Villain may either politely decline, or accept.
If you decline, you may simply say so OOC, but it's polite to give some minor IC so the person doesn't feel like the post was utterly wasted.
Just be absolutely sure to mention in OOC that the person is declined so they don't try to keep playing!
Likewise, you may post 'accepted' in OOC to give the player confirmation of being in now.
Villain said:
(You're in Marie! Let's get started.)
The waitress wanders around a bit longer, feeling the cold night air on her naked breasts. Just as frustration was getting the best of her though, she suddenly spots a small goblin sitting near a dying campfire and masturbating.
Such an encounter was worthy of scoffing at, the thing would've been easy to beat up on with her skills dealing with bar-patrons. Her only concern would be if the thing got its hand on the wooden club nearby before she could reach him.
As she glances past the beast, she realizes why it's stuck out here, a small cave entrance was nearby. The thick underbrush would be a pain to sneak through, but she could if she tried. Watching the beast, she hoped it would stay distracted with its task long enough for her to make her move.
(Paths: Fight Goblin, Combat(Lewd) or Sneak Past, Explore(Combat+Lewd))
The start is a clear acceptance, telling Marie's player she's in. Then it's a direct reply to Marie.
Description goes on for a bit, and she's given vague ideas of her choices, followed by a very clear "Paths" in OOC. Telling her for certain, these are the two options the dungeon has. She can RP variations on this, but regardless of what she RPs doing, one of these must be her action in order for the system to work.
Notice the paths listed are clearly marked. The Primary test is outside of the parenthesis, with the secondary test(s) inside. In this case, the Villain has chosen to force the player to face the goblin one way or another. To actually do this, they would need to pay the cost of making both paths have a goblin challenge on them (more on that when the system is being posted).