One of the less-common Patterns I’ve noticed with games is to take an action which is somewhat abstracted (slaying generic monsters, say) and add personalities and/or ramifications (slaying monsters that turn out to have names and families, you monster). This sort of exercise could be performed on the standard treasure hunt, where the game chastises you for stealing stuff and points out how bad a person you are for playing a game. (This can occasionally be effective but is also wearying in the “you were helping the bad guy the whole time!” plot twist sort of way.)
The opening conceit of Crystal Caves runs along similar lines: having a cave realistically made where touching things will break them and a ranger constantly chastizing you for your plundering adventure sensibilities.
Except here there’s an “inner game” and the change happens, the ranger is never seen from again. (Except, maybe he’ll come back in the endgame?)
You are at the upper end of the misty lake.
You are afloat in a small boat.
There is a large rimstone dam here. Behind it, a pool of water spills steadily over the dam. The ceiling dips into the pool.
This is the location where I hinted at last time that it helps to know something about real caves. I admit my Zork training initially made me think of a human-built dam, but “rimstone dam” refers to a natural cave formation.

Via the US National Park Service.
Because we aren’t talking about a giant concrete structure, the next action makes more sense. I don’t think any rimstone dams are holding back giant bodies of water as implied, but since this is the barrier between reality and fantasy, it works out:
> BREAK DAM
The dam crashes open with a mighty roar. A gigantic wall of water leaps across the lake and down the stream passage, destroying everything in its path.
You have to be careful to stow away your boat so it isn’t swept away, but otherwise, this will reveal the inner game as well as jam the front gate so you can’t go through anymore.
You are in a large hall with a pool of water. To the south, a waterfall thunders into the pool, and flows out through a passage to the east. To the west, a hole in the wall looms beyond a small beach.
You are afloat in a small boat.
The classic Adventure dwarves start attacking you here (and behave exactly as in original Adventure) and the pirate is also active (and will take any treasures he steals to his “grotto”, although I have no idea where that is). The geography is otherwise entirely different.
The Hall of the Mountain King has expanded to nine rooms. In the center is a throne which launches you in the air.
> W
You are in the center of the Hall of the Mountain King, a large octagonal room. There are passages on all sides!
There is a large, bejeweled throne here.> SIT
As you sit, you notice the inscription–“Siege Perilous — Nobles only.” With a fearful roar, the throne hurls you straight up — plastering you on the roof of the cave!
To the northwest is a “bugbear” (although close in behavior to a bear; I think the name is from Dungeons and Dragons but bugbears in that game are humanoids). It is chained to the wall just like the classic one from Crowther/Woods Adventure, but if you feed it, it becomes a “well-fed” bugbear and still happy to attack you.
There’s a “King’s Dungeon” complex off to the southwest leading to a crypt. The crypt has a “Fell King” with an iron crown who will start chasing you if you try to take the iron crown. (You can run all the way back to the throne, where sitting while holding the crown isn’t fatal any more … but it doesn’t seem to help in stopping the Fell King anyway.)
The Crypt also has a “ruby medallion” which I haven’t fulled worked out, but seems to let out a glow every time an enemy is nearby, essentially behaving like the elvish sword from Zork. However, it does count as a treasure, and the Pirate has very grabby fingers, so I haven’t been able to play with it much.
There’s a Wizard’s Tower which you can enter as long as you’re holding a nearby scroll, whereupon you will find a Timemaze.

“p” and “f” here stand for “past” and “future”.
I originally hoped for some crazy “change things in the maze in the past to modify the future” type action, and I supppose it’s *possible* that’s embedded somewhere, but mainly the Timemaze is just a regular maze with two additional exits (past and future). One of the treasures (a scepter) is guarded by a dragon, where the KILL DRAGON trick from the original game doesn’t work. It looks like you can just take the scepter and run if you have some way of resisting fire.
To summarize, my open problems are:
1.) passing the bugbear
2.) defeating / evading the Fell King
3.) finding the Pirate Grotto
4.) stealing the scepter from the dragon
Item #3 is, in essence, the top priority for me because I can’t get much done with treasures being lifted all the time, but “find the hidden place that could be anywhere” type puzzles are intrinsically difficult to just work on.
How a curious and innovative approach for the first phase of the game.
It saddened me when the real game started after just breaking that marvel of nature :)
There’s a way in without busting anything. I hadn’t mentioned it yet because I thought you had to skip a treasure, but it looks like you don’t need to. (Need to test some things on it still.)
Then, this design has my respects.