One 1 -
Swallowing Lemmings Nice level to start off the rank of 1-minute levels. Not that hard to save the requirement exactly, though I rose to the challenge and see how many extra I could save, which is the replay in the collection.
One 2 -
Off-Centered Another easy one, though some bombers I kept placing wrong due to taking the natural progress of going down, left and right, which would be too many losses. Instead, the answer is to bomb to turn back to the left, and then bomb far enough so that you drop onto the gray thin floors and then offset the bombers so that you don't fall too far.
One 3 -
Square Dealing Reminds me of the second level of Mazulems and another variation of it from somewhere else (I don't remember which pack). Another easy one and one which I one-shot

One 4 -
Extremely Lem & Incredibly Close Saved one over the requirement and only used the floater as a delay so that after he finishes digging the builder wall is high enough so that he turns around

Spares a builder as well
One 5 -
Temple Ruins I kept thinking to max out the RR and release the blocker at a time in such a way so that he gets across the gap to the right at the crucial brick placement, but turns out that even when he overtakes the builder the basher doesn't finish in time before anyone turns around. Instead, the answer was to let the builder worker do the bashing and keep the RR at the default to release the blocker with the final lemming. You still finish on time even when the RR is untouched. Nice level!
One 6 -
The Magic Box Ah yes, this level, showcasing lowering the basher continuously with diggers. It's a bit excessive with the repeated digging, and I'm not a huge fan of levels that require too many of the same skill assignments, but that's just me personally. This is nevertheless an iconic level and certainly a trick that comes in handy.
One 7 -
Straight Forward I helped both David and Swerdis with this level from a while back, yet when I came upon this level I couldn't remember how to solve it for about 10 minutes!

Now that I have, I definitely remember having a basher left. Very similar to the Mazulems level, so it's clear that Pieuw got inspiration from Martin Zurlinden.
One 8 -
Baptised with a Perfect Name Another great level. I like how the large wall in the middle at the bottom needs to be bashed from both sides in order to save the most time possible.
One 9 -
Lemmings will be Lemmings... Fairly straightforward, though I could had sworn I used a different solution on Lemmini. I think they both include releasing the blocker on a staircase, but I can't remember.
One 10 -
Bombing the Whole Way Home Ah, yes, I remember this one being frustrating to execute on Lemmini. I also remember the solution being a bit different on Lemmini? I think I ended up building from both sides of the gap? I honestly don't remember, I'll see when I get to the Lemmini version of the pack in the following days. Anyway, first backroute of the rank here, as it avoids the other builder pickup, though I will note it uses a lot of pixel precision to achieve

It's just barely possible and would certainly fail otherwise.
One 11 -
Ice to Meet You Save all FTW!

Don't remember how I solved it on Lemmini, particularly since lemmings don't turn around on steel there.
One 12 -
I See Led People Great level with releasing a blocker with a digger from the entrance, and I love how the timing and solution all work out before anyone gets into danger

One 13 -
Lems on the Lam I remember this level stumping me back in the days. For such a simple looking level, this is a deceivingly difficult one, and as I couldn't remember how this level is solved it took me some time before I did. The miner in particular where it's used to get a climber over to bomb to release everyone from the prison is very hard to see here. I like how one of the climbers needs to go out to the left in order to give the next lemming enough time to build over the gap and then the next one after the builder to bash to the exit. Great solution and level!

One 14 -
Eroding Time Switch Nice level showcasing that a digger can be canceled with a blocker. I don't remember if I first learned this trick here or if I learned it on another custom level from somewhere else. I like how the RR is intentionally set in such a way that the second lemming falls on the other side of the pole to forge the rest of the path

Yes, the digger is super precise here, but that's the only hard part to see and that it's possible to use a blocker to release him and he doesn't become a blocker at all.
One 15 -
In Odd We Trust Should be another backroute here

I'm sure I remember the solution being far more spectacular than this, where I'm certain the climbers go over and then come back later on. However, as the ceiling is deadly in New Formats NL, now I'm not so sure how else the level can be solved.
One 16 -
For Crystal Sake! One of my favorites of the rank!

Nice use of a builder at the top to raise the wall high enough to turn everyone back to the left, bombing to make a hole in the wall to climb into and bash through, then build over the water gap to catch the others in time. Well done, Pieuw!
One 17 -
You'll Make Do ! Another backroute I'm afraid, unless the basher pickup is a red herring

Even then, I'm sure I remember using the basher to speed up the path to the exit on Lemmini, as I think you'll run out of time otherwise. Here, however, it's apparently possible to finish on time even when taking the long way if you max out the RR early enough.
One 18 -
Lines & Curves And we have another backroute in a row here, where if you're careful it's possible to save 1 over the requirement, which my replay accomplishes. I definitely remember the solution being far better than the one I used. For example, I definitely remember bashing through at the bottom before anyone else arrives.
One 19 -
Step on It ! Hard one which I couldn't remember how to solve for a while but it's still a great one when the solution all works out. I kept thinking to max out the RR and use the third to last lemming to block to turn the last two back to the left. This turns out to be wrong. Instead, you must block and then almost immediately assign him a bomber. In the process, two should turn around and therefore speed up doing both sides of the OWW better before the crowd arrives. Here, it's a save all but two solution
One 20 -
There's Rashness in the Method Ah yes, another iconic level that uses a very odd quirk of bashing with the climber during the brief moment when he finishes hoisting on Lemmini. Since this doesn't work on NL, instead the solution needed to be adapted, and this is done by providing two walkers instead. This therefore causes enough of a delay to allow the worker to finish building to the exit on time. Nice level to finish off the rank!