Imagine a dungeon that uses the ideas of Slay the Spire:

3 acts or 4 if you want to do Ki Sho Ten Ketsu

20 minutes each act / layer roughly.

In place of Cards have 3 somethings you can pick from each new room. 

The persist until you pick a different one. 

You can stop at the room you are in.

Come back later.

Rooms might be:

Regular Creatures, Boss, Treasure/Buff Artifact, Merchant, Rest, Risk

Treasures:

Numberous items that you "collect" for the run and persist until the end of the run. Just a buff with an icon. 

Finding this or that persists across the dungeon but can be swapped out at some locations.

Bring friends 1 to 5 since that seems to be your liked limit.

Multiple runs and difficulties. Mostly trashloot with things like caphras or spirit dust. 

Rewards vary from 500 to 1 billion at low tier. 1 to 1.5 for higher tier.

Max monetary reward stops where it stops. 

You can get lucky earlier or have to go through the whole thing. 

Basically gives universal content for old and new players to mingle without struggling over lack of party content.

CHANGE OF SCENERY.

Multiple "environments" needed so it isn't just 'And now another cave or valley' as is the typical.

Not only dirt, rock, or desert.