The prison cells. Unfortunately I don't quite understand what you mean here by "make it clear that lemmings may fall down there". Could you elaborate on that?
Tidal Wave. My brother simply used the Cascade solution, I'm glad you just told me about it again and then proceeded to find a solution with a higher saving rate. I will most certainly increase the requirement on this one. I could either enforce your solution as the only correct one by setting the bar quite high, or I might allow a couple of different ones, too - but just saving 10 like on Cascade is most definitely too easy.
Underwater Hangar. Well, that's just what the updraft on Colorful Arty's underwater tileset looks like

- a dark blue background. Originally, I wanted the lemmings to glide through the exit trigger, but I don't know whether it responds to that. It certainly works for swimmers (see "Splish Splash)". Currently, one can simply build to the exit, so the updraft was a nice little trick to slightly increase the difficulty, making it necessary to cut the staircase behind the builder. Otherwise, the lemmings could just keep walking over the bridge while it is being build, because regular swimmers dropping into water can survive any fall. Being a glider therefore is actually a disadvantage here

.
Apocalems Now. I didn't even know it was possible to make the lemmings walk through a bit of grass on the dirt tileset; I just fenced through the entire thing, used the stoner to turn the crowd around, and then sealed the fencer tunnel again with the builder. Any remaining piece of terrain the lemmings will usually be able to jump over. So it's not actually that precise since it's not necessary to solve the level specifically as you did it

.
Journey to Emeria. For some reason, my brother kept struggling with this level, that's why I left it in. This is one of the WinLems remnants: He struggled with it in its original form, and did so again this time. However, in the end he worked out a pretty nice solution to almost save everyone (replay is attached). With the current saving requirement, you can just let a major portion of the crowd die while building, as both you and I have done (though we took different paths across the landscape). But it is possible to trap the crowd on this level, and I might actually enforce that solution by raising the requirement. Not so boring anymore, is it?
By the way, this is another flavour / allusion level, so the terrain choice wasn't as arbitrary as you might think...
Sneak past the guards. Before you ask me to change anything on this level, you might want to consider what the stackers can be used for

. This idea was also featured in the NeoLemmix introductory pack, so if that's not fair, I don't know what would be

. Both you and my brother used timing / release rate to solve this level, but that is not actually required until Demented 27 ("You can't even"). There's a much easier solution, you just made it harder for yourself

.
Push da button. That was an advanced way of solving it, pushing both buttons with the same lemming!

I was generous enough to give the player two climbers, so the upper one can mine in order to allow the one who dropped down to get back up again. If I enforced your solution by only providing a single climber, that would certainly make this level worthy of Demented difficulty. Apart from that, your solution was actually pretty close to the intended one.
The bee's knees. Well, not everyone has played through as many packs as you have

. Remember that this pack also features introductory levels for the new skills in the Harmless rank; a seasoned NeoLemmix player won't need those either, nor will they need a level like "I got a little trick in mined", because they already know the concept of using destructive skills to trap or turn around crowds. I want to use this pack to teach some general tricks to players; the original game kinda just started demanding these things from the player starting at around late Tricky. If a player couldn't figure it out, later levels were pretty much impossible to solve, as well, because digger traps etc. just became self-evident from then on. People who knew about this idea, in contrast, will have had a much easier time solving the remaining levels, too.
We are not invited?. Yep, same backroute my brother used. The walker was intended to turn around the pioneer lemming sent across the rooftop as a glider - but in combination with pre-placed blockers, the walker of course was precisely the wrong choice for that job

, because it's clearly overpowered here. Now, since I don't want to kill the scout lemming, in order to replace the walker, I have the choice between a stacker and a cloner. I'll probably use the cloner, because it's less obvious. Actually, the original scout lemming does die in that scenario by walking off the screen, while the clone continues the job

.
Help! Get the Ratcatcher! Mmh... they look quite grey for squirrels...

Though I could come up with a different title, squirrels seem less dangerous than rats (again, Magic players might disagree ^^, but otherwise...). What would be feasable way to communicate "lemmings vs. squirrels" - perhaps "Gnaw Wars"?
Buried knowledge. Ok, this one clearly needs more steel

. And while I'm at it, I will add a fifth trap up there next to the exit. Because there's another backroute where the zombies don't have to be used either. So far, no player has used it, I just found it myself by calculating through the skills again: Rather than just fencing towards the exit, as you did it, one could build up on the right, as if to create a path for the zombies, and then there would still be exactly four builders left to build across each of the four traps. A fifth one, in combination with some horizontal steel beneath the traps, should shut down both of these unintended solutions

.
Beam me up, Lemmy! Great! If you couldn't think of a different solution thus far, this means me adding some steel on the left will force you to come up with something completely new at least for this level

.
Diggas in Paris. Good thing the exit is so large that it lies partly outside the Louvre

, so I guess this one doesn't count as "hidden"?
Lems going their own way. Another one my brother solved the same way, the release rate just seems to be too low. I hope it works if I just bump it up all the way to 99.
Synchronized performance. The main difficulty of this level actually wasn't intended; however, oftentimes it occurs that when the fencers come from both sides and the crowd is released, the first lemmings to fall down are lumped together too closely, so no matter who gets to be the blocker, some will always slip by, too many to meet the saving requirement. It seems like you've found a systematic way to get around this; with my solution, this was always more of a trial-and-error thing.
Let down your Lems. This one is a little different: "A staircase of skulls" had a stoner staircase from below, and a rather simple one. On "Filling the gaps", you brought the stoner staircase on yourself, it is not actually part of the intended solution

. In this one, the lemmings on the right are supposed to climb over the pillar (the bombers are required to create a hole for them to go through), and then create the staircase for the crowd below from above - hence the title

.
Maze of Omnipotence. Again: Needs more steel. Thanks for pointing it out to me!
The Lempire strikes back. Looks like I need some kind of trap(s) on the left in order to force the lemmings to go up through the updraft on the right, rather than just building to the top. If you do that, the zombies do actually become dangerous shortly before the end of the level, as soon as the slowfreeze pit (a.k.a the carbonite chamber

) has been entirely filled up. Then they will come towards the remaining crowd and infect them, thereby causing the level to fail if the player has already started to go into fast-forward mode without taking into account that the slowfreeze pit can't hold an infinite number of zombies

.
No idea what you're thinking of! A fine solution, although it seemed rather... painful considering the level terrain

. I guess you can imagine what the intended route looks like...
The ultra-trolling level. Not the intended solution, but certainly one that qualifies for "thinking outside the box". Even I am not nasty enough to make that exit on the left a fake exit, I just wanted to make it nigh impossible to get to. The intended solution is to go across the water (which is actually fire, so the swimmers, which the lemmings on this level naturally are, will die). In order to do that, a combination of builders, stoners, and platformers has to be used. Then the lemmings can get into the exit on the bottom right, because that piece of steel covering the trigger is not actually steel, but just normal terrain.
You can't even. There is actually a more sophisticated approach to this one than trial and error, since it is a rerun

: You can simply go back to the first iteration, "Resistance is futile", you will notice that the release rate on that one is set to a very unusual 18 from the start. That's to make sure it can't be lowered to a point where this level could be solved the same way as "You can't even" - by setting the release rate to 17. 18 is just enough for the zombie to slip by the teleporter while the first lemming gets through. So, starting the trials from the release rate of the first iteration of the level downward will get you to your goal a lot faster than slowly dialing up from 1 to 17.

That's about as much complexity as I could add into a level without any skills. Remaking it would therefore be quite chaotic, 1) because it is a rerun, so it wouldn't make sense to change the physics as much as placing the trap doors elsewhere, and 2) because the distances between the single objects are truly crucial on this one. This level is indeed all about timing, in contrast to the aforementioned "Sneak past the guards"

.
Dark Fate of Atlantis. You're welcome

. Originally, I unticked "no overwrite" for the trap, so it would be visible on top of the stone. But that just looked silly. When I additionally found out that the trigger areas of all this water everywhere render the true physics mode useless for spotting traps, if only for this single level, I just had to exploit that!

Write down the number of seconds it cost you to rewind and place the bomber correctly

. This level is all about execution anyway, there's not much guesswork going on with regards to puzzling, because lemmings can only bomb and stone, i.e. do things that kill them, while they are swimming. So it's more about getting used to these unusual physics that original Lemmings never confronted us with, than planning a route, because the route is pretty much lined out for the player already.
In the original version, without the Disgusting rank, this level was completely unique, and therefore quite a perplexing surprise. Now, "Underwater Hangar" somewhat prepares for this level, but on that level the lemmings can just be allowed to swim around freely. Here, stoners have to be used to press them down. "Shallow water. Diving prohibited" does some work at teaching the player this, since the stoners can be used to dive below the clamshell. But of course, if a player solved "Shallow water" the way you did, by simply increasing the release rate, "Dark Fate of Atlantis" might provide some more headaches.
IT'S FEEDING TIME! I'm just glad I had already added the steel at the top when I released the first version of this pack, because otherwise this level would have had just the most ridiculous backroute ever - just a single fencer, plus perhaps a builder. Looks like adding a little more steel here and there will enforce the long way around all of these hungry, hungry jaws

.
Winter is here. The general idea is indeed to kill the zombies and then complete the level. However, the "frost fire" trap on the right is probably too much of a help for that goal, and even if it weren't there, the zombies would finally walk off the screen on the right - the only remaining issue being the time limit. I will probably remove the frost fire trap and add some kind of unclimbable thing on the right, so that the zombies will keep roaming the level until the player somehow disposes of them himself, without getting the entire crowd infected.
It seems like this time, you only had to wait for winter to pass in order to solve the level

. That might not be possible anymore in the future version!