WTF 1 -
Deep grave maze WTF Yea, I've seen the digger/basher staircase way too many times in the custom level scene now, so not an interesting level by any means to start off the rank. This was just very boring to play too, as it requires it so many times.
WTF 2 -
Builds to victory part three Another pointless repeat of the level, as it's the exact same solution minus the compression in order to finish on time.
WTF 3 -
This is plan B Same thing with the builder/miner staircase, seen this way too many times in the custom levels scene as well. However, I was a dummy here in that I originally tried coming from the left before realizing that it's much easier to do it coming from the right

WTF 4 -
Just a minute falling down 2 Reminds me very much of a Mobilems level on the Lemmini version in the final "extra" rank. This is practically use the "Perseverance" solution of L1 but you have to be fast as time is very tight. I checked your solution after solving this on my own, and very different. However, I did realize that one could cancel the builders to speed up the solution and hence I could had saved some time by doing that rather than finish as the clock runs out exactly.
WTF 5 -
Metal Ark Not a special level in any way, though it is the first unique level of the rank. The hardest part was rescuing the left hatch, though it seems I didn't place one of the miners as carefully as in your solution so that one miner is enough to release the left entrance. Instead, I relied on timing to get someone from the right side to mine and destroy more of the wall so that I could release said entrance.
WTF 6 -
Lightning speed techniques A very hard level because of the precision needed and speed to rescue both hatches before you lose someone, as you cannot allow anyone to go splat due to needing to save everyone. For a very long time, I kept thinking that both floaters need to be on the left hatch, but it turns out the level is impossible to solve if you do this. So, both floaters come from the right instead. Also it's not easy to figure out the minimum amount of builders needed to rescue the left hatch so that you have enough to build to the exit with the right entrance while also making sure no non-floater drops off the staircase. A very nice level, but honestly I wasn't much of a fan due to the rapid fire skill assignments. Then again, I checked against your solution after solving, and turns out I overcomplicated the solution. Big surprise there... not really

WTF 7 -
Palace of Dark showdown Nice final appearance of the level in the pack, although this has appeared way too many times by this point. I especially like the digger pit that must be made with a lemming facing the right so that you don't accidentally release the crowd when stopping the digger with a builder.
WTF 8 -
Orbit platforms A bit harder than the original due to having a smaller skillset, though still not very hard since there's still a lot available. Can pretty much be considered a breather. I later realized it's easier to get up from the right side instead of the left like I did. Oh well

WTF 9 -
Lemmings super hard acrobatics Another very hard level for me, and certainly the hardest version out of any other early version of the level. My solution is very different from yours. Getting everyone down safely was hard and getting up through the structure in the middle at the bottom were hard to figure out. Time is also tight here, though not super tight.
WTF 10 -
Teleportation lemmings One of my favorites of the rank, so I'm in agreement with Turrican here. It was a great fun challenge to figure out how to keep everyone safe without using a builder, as you have enough builders to just use them to build to the exit. Nicely done here!

WTF 11 -
Night crawles onto web Very hard level, so yet another thing I'm in agreement with Turrican on. I use the very obscure basher/blocker trick, and as it turns out it's not required at all. Instead, I missed that one spot on the far right side where it's possible to mine through two walls with just one skill

That would had made it easier for me, but nope, I always kept coming up a skill short. Instead, the obscure trick allowed me to get through three things, two walls and then punch a hole to get to the exit all at once

WTF 12 -
4th Saga WTF The final appearance of the level, this level at least showed me that it's not necessary to turn a lemming around like I did in earlier versions to make a splatform for the upper entrances. Nice use of delays to keep them safe until the bottom lemmings have built across the gaps. Even after figuring out the solution, the main challenge is finishing on time due to the tight time limit. Fortunately, not much walking needs to be done, so it's not too big of a problem.
WTF 13 -
Perfect turning scenario More or less the same as the original, except there's only 1/6 the amount of lemmings and you need to save everyone. Luckily, you have enough to turn everyone around by building and mining to hit steel and then a lot of extra to stall so that the teleporter doesn't overload. I tried to do the same on the original so that I could either save everyone or as much as I could, but I gave up after a while because I think I would had became frustrated eventually.
WTF 14 -
Trap shaft Second unique level of the pack. Another breather level, though that's because it's possible to get up on either side and then careful use of the destructive skills to come up from below to reach the exit. These solutions are easily blockable with either more steel or OWAs pointing in the "wrong" direction so that you can't bash through.
WTF 15 -
Castle maze Ah, this was another hard level and gave me a lot of problems just like the original. Once again, my solution is very different from yours but I had more miners available to stall the others so that the teleporter doesn't overload. However, turns out I completely missed those who do go out the wrong way in the teleporter can actually free themselves later

No wonder I had so much trouble even though I initially had the right idea to go through all gaps at the bottom. Also not realizing the excessive miners are for stalling for a very long time. I kept using them to tank on steel to turn which I guess is technically stalling as well but the wrong kind for this level.
WTF 16 -
Teleportation lemmings part two Not an exact repeat of WTF 10 and the original due to layout changes, but it's clear it's based on the same idea. This time, the use of the far right teleporter is enforced. The only hard part is figuring out that the RR needs to be maxed so that the teleporter in the starting area overloads to allow the second one to turn back to the left and build to the exit while everyone else takes the very long detour. So, this one was a quick solve and easy IMO.
WTF 17 -
Factory of fears Nice unique level here, with the only hard part timing the climbers to block to turn the builder three times. Also, one must be careful with the amount of bombers used, as the first time I used too many and hence fell short of the requirement. So really, do the top middle efficiently and it shouldn't be a problem. Also, I would reduce the amount of lemmings here, as assigning the climber skill 40 times is just too excessive IMO. It would be a much better level this way.
WTF 18 -
Speed staircase scenario As mentioned before, the basher staircase idea has been overdone to death in the custom levels scene, and so this level isn't interesting to me in any way. This level requires it way too many times for my liking. The same idea can be done with a shorter wall. It was satisfying to beat the very tight clock, but yea, this isn't anything too special, at least for me.
WTF 19 -
Lightning speed lemming express At first, I thought the solution would be the exact same as the original and hence would be another pointless repeat. Turns out the solution is slightly different in that the crowd cannot go through the OWW due to the much tighter time limit. Definitely still has the Crazy 4 vibe here. This would probably be the better one to leave in the pack, though both this and the original are great.
WTF 20 -
Miners in hellsfire The only difference from the original is that the blockers have been replaced with miners, meaning you just have to cancel the miner each time with another one, which is a bit harder to pull off due to how very precise it is. I don't understand why you're allowed up to 10 losses though. If anything, it's very easy to lose just 1 and as Turrican has shown a save all is possible, though I kind of suspected it is, I just didn't think about going for it here
WTF 21 -
Two different worlds part two Another favorite of mine of the pack!

As mentioned before, I love builderless levels, and just like the original, the left half is harder than the right half. Because you don't have climbers or builders, the only way to get up the level is to use the terrain. Nice to know there's still multiple ways to do either half, though you still have to be very careful on the digging destructive skills, as they might seem abundant but run out surprisingly fast. Again, I really enjoyed this level and the original!
WTF 22 -
Its all matter how you succeed Definitely harder than the original, though I initially tried some messy stuff that looked like the solution was going to be annoying and fiddly to do, but turns out there's a much easier way by containing the crowd and sending out climbers as necessary to bomb and build over each gap. This definitely reminds me of a LPI level where you do something similar on the repeat, I think?
WTF 23 -
The Gunship Showdown The final appearance of the level, though once again pretty much the core of the level's still the same, just the way to get down safely without the aid of blockers to hold the crowd back. As such, definitely the hardest version of the level. Even then, I'm sure there's still multiple ways to do the level, such as building to get over the top and using the far right of the level to get down and still have enough builders for the level.
WTF 24 -
Lemmings bashing race part two This level has appeared more than once before, though one of them is more of a remake of the original due to layout differences. This is quite a great one and very satisfying to beat the clock. My route is different from your solution, and it seems that I dismissed going out to the right on the starting platform too quickly as impossible due to the time limit

It's quite pixel precise to make the splatform for the crowd anyway, as you pretty much have to build at the right spot and also make sure no raised bump is left after bashing through the wall to the left. Still, this is a great level and I like it a lot.
WTF 25 -
Temple of rotations Another great level!

The hardest part to figure out was how to go over the top in order to destroy the final OWW before the exit. My solution is very different from yours, mostly due to going for a save all which fortunately is possible but uses up all the builders. Here, I failed to realize to use more stalling so that no lemmings go out the receivers in the wrong direction, and instead I made turnaround points to avoid going into the traps in case they do. Again, great level.
WTF 26 -
The bash controll Not a bad level, but the quality suffers significantly due to the many hidden traps. Most of the NL community will tell you to make the traps visible, as hiding them otherwise with absolutely no indication as to where they are without turning on CPM is frowned upon and considered unfair design. In addition, CPM renders hidden traps pointless, as one click and all is revealed

Once again, my solution is different, and I was fortunate that the climbers were sufficiently spaced so that the other one turns around to bash through the first OWW. Personally, I would replace the shredders with the acid pits and make open windows so you know where they are.
WTF 27 -
All in one group I thought this was going to be quite a challenging one, but it wasn't as bad as I thought. Again, my solution is very different from yours and is even the most saved possible, which is lose 1. It does require that the lemmings be sent out as climbers at the right time though.
WTF 28 -
Lemmings Expressline Trinity Definitely a backroute I found here, as I do not build over each gap at the bottom

As I thought, the intention is indeed to use a builder per gap, but I didn't want to bother due to what I thought was going to take a while and fiddly solution. Instead, I resorted to a builder wall to contain the crowd instead of keep the crowd moving

Seems like the only way to enforce the intended solution is to make several of the builders pickups

WTF 29 -
The Frozen inferno Good challenging level where you first need to deal with the splat hatches and once you do so then you're pretty much free to carve out your own solution while making sure to be careful to not run out of skills.
WTF 30 -
Lemmings Revolution Yet another nice challenging level, though honestly I'm not a big fan of the music track here

It made it quite difficult to focus on getting the level solved, especially the scatting vocals. I think my first several attempts I made it impossible to get the non-climbers up to the exit, as I didn't have enough of the right skills to do so. However, once I adjusted how I did the beginning and some skills around the middle area, then I had better success. Definitely a very nice final feeling kind of level here to finish off a great pack!