I run theatre of the mind, often somewhat improvised. Exploration is hard, particularly if you want there to appear to be any logic involved.

I use a very broad rule for myself, excepting dungeons. Any location should have three branching exploration options at most three levels deep. That means you can fully explore a location in at most 9 rooms. A branch should proceed thematically, and I will often wing it. Not every room needs and encounter, but every room should be interesting. Rely on senses other than sight to add flavour.

Example: a mad wizard's cottage in the woods. Description: "you enter the foyer, and there is a door to either side, and stairs leading up to a mezzanine. You can smell something dank from the left door and you can see some bookshelves at the back of the mezzanine. The right door appears unremarkable."

It's entirely trivial now for the players to decide where they want to explore. Three branches. The unremarkable door can be a bedroom or storage closet or something. The stinky door can be a kitchen that was left untidy and became mouldy, with a backroom that leads to an overgrown greenhouse now home to a shambling mound. The mezzanine can be a library with a workshop behind yet another door, and a hidden door behind a bookshelf going to a room that only contains a standing mirror.

Fuck, this sounds interesting. Wizard has been gone for a while, where? Maybe through the mirror? What was he working on? Etc.

In a four hour session, we'll be lucky to get through two or three such locations, depending on whether combat is involved. Over time, I assemble larger threads from almost entirely improvised beginnings, so I can make callbacks.

Maybe thinking about the exploration in your game as a point crawl could serve you well.

Think up a bunch of interesting locations and encounters for your players to experience, then for each encounter/location roll 1d4-1, that is how many other encounters it links to, randomly pick from your other encounters/locations for each link.

For how to generate the encounters/locations there are many tool sets to draw ideas from. Books like the Tome of Adventure Design, Worlds Without Number, Knave, Shadowdark, etc. Online tools from don jon, hexroll, or others.

Let me know if you would like other specific recommendations and happy gaming!

I'm a bit unclear on what you're looking for. Is it like totally randomly generated dungeon dressing? Because my idea would just be to improv the dungeon dressing of a room or hallway based on what you know the room to be used for.

Like if you know the room is a kitchen where the cook was murdered, you can describe a bloody dead body in the corner, a bloody knife, etc.

If stuff is 100% randomly generated, wouldn't that just break the verisimilitude of the space?

I almost never use battlemaps and when I do, it's more a way to provide some decorum and structure informations rather than as a tool for battle. I don't really get how so many people online are obsessed by the idea of battlemap. Looks like kids this days have it too easy and didn't started playing at the time where RPG magazine was publishing 3 scenario a month, with sometimes one for a game they play, and had to do without map in general.

A few idea pointers,

• I played Ryutama only once, but remember their concept of battle egg which just tell whether you're in contact, second-line, ranged distance or away using a few circle. Nobody care about your exact distance, but just use some adjective to describe your position.

• As usual, PBTA and forged in the dark, can use consequences to generate danger, like you open a chest but choose one : Someone has seen you/ A trap trips/ Move to a worse position

• Even in traditional game, you can describe the dungeon with a few adjectives, and by thinking what it's for and answer the players question when they ask-it rather than in advance: Can we enter by the sewage ? Well there is a garnison in this castle, it's near a river, people need to piss and shit, so most-likely there is a pipe going directly to the river, let's say yes. However people are not stupid so there is some metal bar to block the access, the player can try to break them works as well as doing a map and thinking about the 5 possible way to enter while the player will use only one.

...cubicle 7's uncharted journeys does exactly what you're describing: it abstracts the exploration pillar into a series of encounter vignettes driven by characters assuming leader / outrider / quartermaster / sentry roles to engage the system mechanics...

...while it absolutely can be adapted to old-fashioned hex-crawl resource management, uncharted journeys is written to support exploration as a theatre-of-the-mind montage sequence, accounting for preparation + decision-making with tangible consequences upon reaching a journey's end...

...it's good stuff!..