WillLem, I know how you feel - it's been just a little more than two years since I joined the forum, and this reads like a déjà vu for me now. 
There definitely is a "market" for the types of levels you currently seem to like - however, it's often restricted to older versions of NeoLemmix. But since you don't seem to have a problem with that in principle, given that you're also still using SuperLemmini, you might also want to try out these older versions of NeoLemmix?
The latest stable version before any major change is still available on the NeoLemmix homepage, precisely in order to allow people to continue playing older packs.
Levels for NeoLemmix 10.13 (colloquially known as "Old Formats") 
SubLems (by Colorful Arty). This pack exists for SuperLemmini as well as for Old-Formats NeoLemmix. Many levels in this pack look like paintings, e.g. a big lemmings train, the face of a toad, a clock etc. It also contains some hidden exits for flavour reasons, as well as flavour-based invisible or otherwise misguiding terrain (like on a level called "What would Jesus do?"). The SuperLemmini version abuses "quirky behaviour" of certain skills to an even larger extent than the NeoLemmix version.
You can watch the creator's Let's Play of the SuperLemmini version here:
https://www.youtube.com/watch?v=uA77Des9Tus&list=PLQHiUcBinBlCS6bwKnmcqkmRaI_4kevcmAnd here's Flopsy playing the NeoLemmix version:
https://www.youtube.com/watch?v=zafOBg6qnj8&list=PLXsuXbpwwJzFYUTTXx34I5nSKR-UZS0ZBCasualemmings (by nin10doadict). This pack deliberately aims for a lower difficulty, plus it contains a dedicated troll rank (which is now apparently called Quarantine?).
Paralems (by me). This was my own very first level pack - from the time when I myself considered hidden traps and exits to be fun.
Like in your case, I considered it perfectly plausible from a flavour-standpoint where on a level these hidden traps and exits would be located. This pack in particular is especially (in-)famous for turning pieces of terrain that look like animals into traps, so that the animals can actually eat the lemmings. The abovementioned Casualemmings by nin10doadict also includes a level as a homage to me
, where nin10doadict did something similar. Paralems also includes my ultimate trolling level "Trust No 1".
Levels for NeoLemmix 1.43 (even older)GigaLems (by GigaLem). This pack is only available for NeoLemmix 1.43. This version had no skill shadows, no Fencer or Shimmier skill, and, most importantly for this specific pack, no clear-physics mode yet. If you want to experience hidden traps and exits in all their unfair glory, go and try this one!
According to GigaLem himself (mentioned during a guest appearance on Colorful Arty's Let's Play of Flopsy's SEB Lems), he got IchoTolot to ragequit on these levels. This doesn't mean this pack doesn't contain a lot of good levels, it really does - but it also really offers a great demonstration of how frustrating hidden objects can become if you can not simply unveil them with the press of a button.
Lemmicks (by me). Here I tried to find a compromise by taking literally "gimmicky", game-altering level design elements and making them as fair as possible through prior anouncement: Each rank features a different gimmick altering the game rules in a certain way, but since it's consistent across the entire rank, the player has time to adapt to these changed rules.
What I've learned in the meantime is that flavour-based logic only goes so far in trying to convey to the player where there might be hidden traps or exits, or invisible terrain, or manual steel areas. Even with famous pop culture references, such as Indiana Jones or, as I did for my pack "Paralems", Game of Thrones, you can't rely on people knowing this stuff, especially given the small size of our community.
Animal traps are something that people have come to expect and accept of me, I guess
. But I've found you can still make these more unfair than others by putting trap trigger areas into water or updraft trigger areas, or other stuff that's also coloured pink in clear-physics mode.
The idea is that the player runs out of builders before getting to this part of the level, but (hopefully) discovers that they are able to walk across anyway!
This is something that seems completely plausible when coming from a game like original Lemmings (sold back then as an "action puzzle"), or adaptations of it that still stick more closely to the original, like SuperLemmini:
You're used to approaching levels on a trial-and-error basis.
In the NeoLemmix community, however, there are a lot of people who solve levels entirely in their head before the hatch even opens.While I personally find this approach too radical - there are a couple of things which require you to play a couple of seconds into the level to get the necessary information, like for example, in case of several hatches, in which order they release their lemmings -
putting a misleading element at the end of a level makes any type of advance planning completely impossible.
The go-to example of this is a hidden trap at the last moment before the exit - in your case, it's the opposite: a hidden aid to solving the level, rather than an obstacle, but still one that you only find out at the last possible moment, and therefore, you have no chance of incorporating it into your planning of the solution.
In contrast, putting such elements at the beginning of a level will at least make the player find out rather quickly.For example, many people got confused about my Paralems level "Skies aflame" (also appearing on the Encore rank of Lemmings World Tour), because they didn't know the lemmings were Swimmers right out of the hatch. I wondered how anyone could not know this, because you see it right away as soon as the hatch opens. But of course, if you're one of the players who plans the entire level in advance, you don't. That's why they asked me - and told me about the common practice back in the day - to label my hatches with (fake) pickup skills. In this case: Putting a Swimmer pickup skill above the hatch.
Instead, I responded by showing the futility of hatch labeling, creating the level "Beware of collectivism" for my following pack, Pit Lems - where I put several hatches on top of each other (a common practice to have lemmings come out facing left and right successively), but with different skills pre-assigned to them (Floaters, Climbers, and Swimmers, for example).
Now that there are different types of lemmings coming out of the same hatch, how is anyone supposed to label these hatches?
Meanwhile, in New Formats, hatches are pre-labeled no matter what if they have pre-assigned skills, and while labeling them with pickup skills on top of that is still possible, fake objects no longer exist, meaning any pickup skill you'd use to label a hatch could actually be collected by a lemming, which could end up breaking your solution.
So, as you can see, I'm still somewhat of a rebel and refuse to completely "bow" to people who might feel entitled to being able to figure out the entire solution to any given level in their head and having to execute it only once. But making such an advance-planning approach completely impossible would be the other extreme - and would drive those players away from your pack, further limiting its outreach in an already small community.namida hit the nail on the head with this statement, I guess:
And that's where the problem lies - it is indeed an interesting concept when it's done once. It's just annoying when you encounter it for the 100th time. And most of us here have had those first 99 encounters by now...
To be clear, no-one wants to deprive you of your "troll phase" (not to be confused with a troll face ), because, as namida stated, every new Lemmings content creator goes through this phase.Knowing that there are also some Magic: The Gathering players on the forums, I'd compare this to what MTG players call the "healthy Timmy phase". Timmy being a term used to describe a somewhat-newbie who still enjoys beating up their ingame opponents with huge, flashy fantasy monsters, even though, as most players learn later, there are usually much more efficient and "professional" ways to win at the game.
However, if your goal is to quickly increase the outreach and popularity of your packs, then it's somewhat useful to "desensitize" yourself to the appeal of troll elements - by putting yourself into the player's shoes.Go ahead and play some GigaLems, or have a look at what I created for Paralems when I though hidden objects to be fun - and then, after having encountered such stuff a couple dozen times, simply judge for yourself whether you still enjoy this type of level design.
And to be clear, I'm not pushing you in any specific direction by saying this - in the end, it still comes down to personal preference. But I can definitely say the novelty of hidden traps and exits wears off, and with everything, as novelty fades, so does the "fascination" that comes (and goes) with it.
