vault_chance     = 9;

    if (!player_in_branch(BRANCH_MAIN_DUNGEON) && one_chance_in(vault_chance))

    if (!player_in_branch(BRANCH_MAIN_DUNGEON)
        && vault_chance
        && one_chance_in(vault_chance))

    switch ( feat )
    {
    case DNGN_DEEP_WATER:
        if (you.species != SP_MERFOLK)
            return "This deep, misty water will drown any who set foot in it, "
                "unless they feel at home in water. Nothing in the dungeon "
                "-- not even you! -- is dumb enough to go there without "
                "thinking twice. Except when they're really confused...";
        else
            return "This is the deep, misty water which you call home.";
    case DNGN_FLOOR:
        switch (random2(6))
        {
        default:
        case 0:
        case 1:
        case 2:
            return "A plain floor space, for walking on.";
        case 3:
            return "Just a floor. Walk on it. Fly over it. I don't care.";
        case 4:
            return "A plain floor space, for walking on. "
                "It could contain a nasty trap, but "
                "who would be paranoid enough to believe that?";
        case 5:
            return "A plain floor space, for walking on. "
                "Perhaps an invisible creature is lurking there, "
                "but then, the dungeon is no playground for the "
                "superstitious.";
        }
    case DNGN_ENTER_SHOP:
        return "A shop! Here, of all places! Some souls question the "
            "wisdom of the dungeon's shopkeepers, who import wares to "
            "hawk among a populace nearly as penniless as it is merciless. "
            "But then, you're here and itching to spend, so... "
            "what's the problem?";
    default:
        return std::string();
    }

    return std::string();

    desc += getLongDescription(desc.substr(0, desc.length() - 3));

    desc +=
        getLongDescription(grd[x][y] == DNGN_ENTER_SHOP? "A shop"
                           : desc.substr(0, desc.length() - 3));

The typical dungeon barrier. Though it is impenetrable at first sight, there are several ways to get through or around it.

An impenetrable barrier. As every dungeon electrician knows, it grounds all forms of electricity.

A wall of bluish-grey metal.

These walls are built by bees. Occasionally a dungeon architect will manipulate bees into building wax walls for esthetic reasons. (Theirs, not the bees'.) They are susceptible to heat and can easily melt.

These walls are built by bees. Occasionally a dungeon architect will
manipulate bees into building wax walls for aesthetic reasons. (Theirs,
not the bees'.) They are susceptible to fire and will melt and burn, given
sufficient heat.

Lava, like the smoke that billows from it, sure looks pretty from above! But walking on lava will burn everything but lava creatures to a crisp. If the lava creatures themselves haven't already done that job at range, that is.

An intensely hot pool of molten rock, emitting clouds of sulphurous smoke.

A shop in the dungeon, beyond sight of the world above, manned by a
secretive and reclusive shopkeeper who cannot be bargained with,
grants no refunds, and is interested in nothing you may have to sell.
Some shops hawk antiques of unknown provenance, and offer little hint
as to the quality or nature of their goods.

A gateway to an intricate maze designed by subtle and malicious minds,
its exit guarded by a fearsome monster, where many a hapless
adventurer has lost his way and starved to death.

A one-way gate to a demon-haunted realm, riven by chaos, its very
substance impermanent and whimsical, filled with creatures out
of nightmare.
"And if you gaze for long into an abyss,
 the abyss gazes also into you.”
    – Friedrich Nietzsche, "Beyond Good and Evil"

A gateway out of this accursed place, shimmering and shifting in the
impermanent landscape.

An entrance to the mines of the orcs, filled with their gold, but
treacherous and easy to get trapped in.

You hear an angry and manifold drone.

An entrance to the Temple of the Gods, a place of peace and refuge
from the insanity of the dungeon.

Here is the way to the place of the serpent, the lair of the naga.

A wide stair down to the murky depths of the halls of the deep elves,
skilled warriors with blade and bow, and fearsome sorcerers and
magicians.

A way to the Tomb of the Ancients, a place of damnation, of horrors
animated by the vilest necromancy.
"In the depths of every heart, there is a tomb and a dungeon, though
the lights, the music, and revelry above may cause us to forget their
existence, and the buried ones, or prisoners whom they hide. But
sometimes, and oftenest at midnight, those dark receptacles are flung
wide open. In an hour like this, when the mind has a passive
sensibility, but no active strength; when the imagination is a mirror,
imparting vividness to all ideas, without the power of selecting or
controlling them; then pray that your grieves may slumber, and the
brotherhood of remorse not break their chain."
    - Nathaniel Hawthorne

A stair to a swampy waste land, complete with ooze, muck, flies, and
large slavering carnivorous monsters.

Here be the Shoals: exotic underground beaches, salty spray and
creatures that bite, stab, and maul.