I just try the four levels that were mentioned as impossible. (I downloaded the levels by following minim's link )
A Higher Platform and The Top Card are outright impossible. They are short by one or two skills. Statue of OilDrums is probably impossible as well. I did find a solution for The Lem Stairwell though.

Played through the contest levels 

No Way In Hell

The level looks simple with a minimal skillset, but the solution is well hidden. Watching a basher slide down a builder bridge is always satisfying!

It's Crazy Sports Day!

Nice level with two similar interesting tricks. First, you park a lemming with a blocker and later release him using a digger. Second, you temporarily store a lemming as a bomber and release him with a miner directly toward the exit.

Social Distancing

It's a cute little level where two lemmings work together back and forth to build the path and reach different exits. Since I thought the rule was tricky to satisfy without using buttons and locked exits, I really like that you managed it without them.

Help Me, Help Dune

Once you recognize the big miner extension everything falls into place nicely. I love how the two lemmings work in opposite directions at the same time, then eventually swap positions and reach the opposite exits.

Lem In The Box

Probably the hardest level in this contest... though still nothing too tricky. Diggers are the most valuable resource here, so picking up as many digger pickups as possible naturally leads you to the solution.

We Got Mad Lemmings 3 Lab Skills!

The well-placed miner was the key to solving the level. It single-handedly gathers the whole crowd and also creates the path to the exit.

@crane
Your solution is close enough. So close that I consider it intended

I didn't think the vote would be this close. I almost want to add both tilesets to the list.

Brick and Dirt are my two favorite tilesets, so I've used them the most here and there.
Fire, Marble, Rock, and Bubble were already decided to be used in this level pack.
There are also many Snow levels in my previous xmas-themed level pack.
So Pillar and Crystal are the two tilesets I've used the least so far.

Whichever tileset wins the vote, I'll use it for the second rank of this pack.
That means it will be used to create simple puzzles rather than complex ones, and levels where you explore wide landscapes with plenty of skills. Both tilesets are excellent for creating scenery.   Crystal feels more polished and mysterious, while Pillar gives off a more classic and traditional vibe.

Once the final voting result comes out, I'll make a level using the winning tileset and post its picture as a sneak-peek of the tribe. After that, I'll quietly continue developing the level pack for a while. 

@Crane
Hey thanks for the compliments and you found the intended solutions to both levels

@Crane   

I can give you(and someone else!) some hints on my levels:

R1: Pretty much every skill already has a fixed place to use, except for one or two - and those are the key to solving the level.

Spoiler

You should start by sending one worker to the left (give him a climber and a floater + use a blocker to contain the crowd). The worker's first task is to dig down. Where to dig is the main part of the puzzle and once you figure that out the rest of the solution will fall into place naturally.

R2: I thought my R2 was the easiest one. I crammed a bunch of new NeoLemmix quirks into it, so the unfamiliarities may have added up and made the level feel trickier than it actually is.

Spoiler

First, the two workers must meet on the lower floor and build a bridge together. After that, one of them should go back upstairs to complete his own task.

R3: This one is a bit difficult, I agree. First, you have to figure out which pick-ups you actually need. Some of them look easy to reach and seem to require only a few skills, but they're actually dead ends.

Spoiler

Near the starting area, there's a pit with a basher pick-up. You need that basher, but you can't let the crowd fall in and get stuck, meaning you must send only one worker to collect it, and then save him with a climber. You also need to collect one floater. There are two floater pick-ups in the level, but one is a red herring. The one in the top-right is the red herring.

I've added a poll

There're currently five L1 tribes: Brick, Bubble, Dirt, Fire, Rock.

I'd like to add one more tribe with one of the remaining L1 tilesets.

Which L1 tileset do you prefer to see in my in-dev pack?
I'm tossing up between crystal and pillar...

crystal - artistically beautiful and versatile, visually stand out
pillar - least used tileset in my levels - can explore new possibilities

Your vote will be appreciated

PimoLems was already ahead of its time, but this one is even more stunning 

October 30th, 2025 Update
reach the 120 level mark 

This pack will likely features 15+@ tribes, and each tribe will have its own unique theme. Though unlike Lemmings 2: The Tribes, this pack won't strictly restrict which skills each tribe can use, instead, I've tried to give every tribe a different flavor and personality through their themes.


Here are some examples with screenshots :



Dirt Tribe – "Back to Basics"
This one's all about classic Lemmings vibes! All levels use only the original 8 skills, and many of the solutions are inspired by the old-school levels from the original game. Overall difficulty is: pretty easy.


Dirt - The Safest Bridge in Lemmingland
what did you say? the safest bridge?


Basset Tribe – "Swimmer Puzzles"
These levels are all about experimenting with the Swimmer skill. You'll find lots of water pools and will need to come up with creative routes using Swimmers. Maybe even tackle a level that's almost completely underwater.
Overall difficulty is: on the easier side.


Basset - A Theatrical Songbird
built different, taking a different route!


Cloud Tribe – "Movement Skills"
Here you'll make good use of various movement-based skills to hang around hard-to-reach-normally places. Combining these skills in clever ways is the key. Expect some dynamic and action-packed levels!
Overall difficulty is: Most levels are fairly easy, though the last few might give you a headache.


Cloud - Platform Nine and Three-Quarters
run through a brick wall!


Space Tribe – "Teleporters & Receivers"
These levels feature one or more pairs of teleporters and receivers. You'll need to travel back and forth through them to open up new routes across the map.
Overall difficulty is: very challenging


Space - Galactic Civilization
something... only advanced civilization can do!


Metal Tribe – "Weirdness"
This tribe is... well, weird. Expect eccentric, unexpected solutions where your usual Lemmings logic might not work. You'll need some out-of-the-box thinking here.
Overall difficulty is: unpredictable, it really depends on the level!
(If you've played my previous pack Lemmings Halloween 2023, think of the level "Insulator", that one would fit in this tribe. )


Metal - Insufficient Data for a Meaningful Answer
self-explanatory...


Renaissance Tribe – "Extreme Difficulty"
This tribe gathers levels that were just too hard for my other packs, or made just seeking self-satisfaction, or ones I decided not to submit to contests because they were a bit too overtuned. These are the most complex and challenging puzzles I've made so far.
Overall difficulty is: never seen before


Renaissance - Romanticide
put their spirits to rest.. but not me!




There are many more tribes with various themes, hopefully I can showcase more of them next time.. maybe when the next wave of motivation hits.

This time, this should be intended  (plus a similar but backroute-ish alternative solution )

resolved updated levels 

Spoiler

Eon2, Eon5 - look intended for me now
Neo1 - probably intended? since you said the intended solution is counter intuitive and I made the turn-around point farther and save more time as a result.
One2 - looks intended
One5 - another nuke solution.. I'm pretty sure the intended solution has some kind of nuke interaction in it to compensate the lack of destructive skills, but I'm not sure if this is the one you intended.

resolved updated 3 levels 
These look mostly intended, except for autopilot level

Here're my solutions. I guess I backrouted two or three levels.
This pack really shows how much puzzle potential the new objects can provide.

I just played through the pack and here're my replays. (two replays for One_3 and one replay for every other levels each.)
I managed to save multiple lemmings on only one level "Aquarium Deception". The talisman said save two but I managed to save most of the lemmings.
There are many good levels but my favorite was "So many Spikes", that was a brilliant level

also added new packs to the list
If there're any missing packs, let me know!