Just to break things down for clarity:
Portal based: works
Varying difficulties: sure
Fully random layouts: I assume you mean, “no two areas are the same”, if so yes.
Hidden/locked rooms: yes depending on theme, though dda players are going to expect to be able to subvert this sometimes with e.g. explosives.
Biomes: yes
Static monster population: yes, though note my “or appear accoring to some logic” in the previous comment. Trifids and fungaloids could be growing reinforcements in a special room or from a boss creature, nether creatures could be making new tears and sending reinforcements through them, etc.
Freely return to previous floors: yes, and should include exiting the area entirely.
Description indicates difficulty: yes this needs to happen, particularly if some of them have extra hostile environments (requiring breathing apparatus or environmental protection).
Definitely this, it’s a very thematic way of handling the issue for dda. You should also start getting signs that the portal is getting unstable to warn you to get back out. Ideally we’d have some kind of progression where when portals are introduced, a number of short-lived ones spawn that illustrate to the player that they have a risk of closing on them.
Basically the placement should be logical, you shouldn’t just encounter piles of good stuff at random, there should be some logic to what appears where, some examples.
Corpse of a human with gear on it. This should be rare but can range frm meh to very good (e.g. full power armor).
Items harvestable from enemies.
Alien tech/artifacts.
Items collected from Earth (can be random with some very good stuff mixed in like minireactors).
- Interesting side note, collector aliens could be searching out certain things, like books, fissile materials, rare earths, etc.
In short, I think the best option is to have a small amount of very high end loot, it’s hard to come up with a rationale for there being a lot of conventional loot the player wants, it mostly needs to be exotic.
We’re not reworking how artifacts are generated to make them unusually good. The whole point is finding artifacts with benefits you want and down sides you can tolerate. There cold be some non-artifact alien tech though, that operates on its own logic and has minimal downsides.
This kind of thing needs to be made thematic, perhaps you can acquire an item in a lab that extends the duration of the tear, or re-opens a recently closed one. Both of these would only make sense to operate from the source of the original tear though.
