Taxing 3 I, Me, Mine, Miner : One of my favorites. I'm usually not that good with miners, and this level taught me again how  to use them as delays, really nice.

Taxing 4 Symmetrical Structure System : Backroute I think ? I save 79/76 and spare many skill : just build a giant splaform by escaping a athlete, and free the crowd by a nice bomber.

Taxing 9 Slow Esthetics : This was hard to me ! Using the floaters at different places to allow builders to set up 2 bricks instead of one before the next lemming come was the key. Frame precise but fair I'd say.

Taxing 10 Pillar Confusion : those pillars are indeed confusing, great design ! Backroute again I think as I save 24/22 and have leftover skills. A single worker was enough, the long digger at the beginning helped a lot.

Taxing 14 Bubble Trouble : Mean time limit ! I had to use not less than 5 workers at the same time, so this level must please kaywhyn ! I end up with many skills left again and save 20/15 at the very last second, so this may be unintended.

Mayhem 8 The Law of the Jungle : I save 79/76 by going straight to the exit. The crowd is freed by using the pixels removed above a miner's head when it starts.

Mayhem 12 Shorty Deep Inside : I spare a miner and a floater in this very limited skillset. This is possible by catching all those not-so-close climbers with a builder, but it is frame precise and needs many tweaking on all required lemmings.

Mayhem 14 Lemmings Fever : I love this 1 minute level ! There are so many solution without the timer, but I guess only the most efficient of them work in under a minute. I loved the use of the bomber.

Mayhem 15 It's All About The Style : Excellent level ! The use of the diggers to free the blockers at the end is very ingenious, took me a long time to find.

Mayhem 16 The Scaffold : Is that a backroute ? I save so many skills that I think it is. Hardest part was to figure out the left blocker.

Mayhem 18 The Enigma : the miner extension was a must to spot. My way of sneaking under the OWW in the middle looks unintended. It saves some skill and does not use the rightmost part of the level at all.

Mayhem 20 Kreuzung At The Mountain : I love this marathon level, mainly gotta get the left lemmings to the right exit, and conversely, with nearly unlimited builders. I played it several times to try to optimize and could save 99/95. Could not make 100% save though but I'd say it is doable.

Mayhem 21 Enter At Your Own Risk : I agree with Icho and others here : this level is great. Nuke solution did not occur to me that fast because the save requirement of 72/80 is pretty high. So one has to optimize correctly to reach it, but execution is not hard actually once you know how.
This reminds of a certain One 5 level in the Save One pack, though I certainly created it before playing this Mayhem 20.

One extra Lem saved, certainly by sparing a bridge over what's intended to stop the miner before it falls to the bottom.
To achieve this you have to place the bomber, miner, and 2 builders in pixel-perfect places. See solution if interested.

I did not stop the laserer, in my solution it destroys the platform with the button on it, but then I overcome this with a well placed basher.
In the end your solution uses basher+laser+jump, where mine uses laser+basher+jump, so we're equal here.

But then I maintain that the steel definitely stops your laser. Later this allows you to save another skill and then have that builder left at the end to turn the slider around to the exit.

On my side I turn the slider around with the walker pickup, which is why I think my solution is intended whereas yours is backroute : laser stopped by steel is not intentionnal by designer Mobiethian/kaywhyn. Let's see what they say !

I also had to choose where to use the jumpers carefully. In the end I did not cancel the laserer because the extra basher allows for making the slight space needed to access the second button in a single jump despite the laserer hole.

I think I have the intended solution because I do need the walker pickup at the very end, to save the cursed slider.

The hardest part for me to figure was that one actually needs 2 pionneers to make it at the end : disarmer cannot be slider too. So isolating 2 lemmings at the beginning was necessary, and the weird part where one needs two builders to reach that leaf on the wall makes perfect sense !
So yeah, I guess this is intended solution ?

How did JJ stop the laserer ? Is it stopped because it meets steel by like 1 or 2 pixels ?

1 : the pack starts hard ! Very well know level with what seems an impossible skill set at firts. Though the very few number of skills given does not leave many choices, and once the digger spot is found, the rest is ok.

2 : nice little puzzle. Walker is strong as usual, and I am left with climber/floater pair, old style Lemmings !

3 : first roadblock to me, I was trying to go the bottom route. I created a half turn with a single pixel digger, I guess this is intended.

4 : I learned the half-turn with stackers here, thank you !

5 : I could save all Lemmings with many digger cancelling in the rightmost pillar. Maybe not intended ? Did not try the Talismans, especially the timed one.

6 : Just dig at the correct place, kind of easy.

7 : Two builders only. I made the first bridge so that the builder turns around and only the last lemming goes up. This saves a lot of time for the second builder. This is one of the level where solution is hard to execute, and pixel perfect.

8 : I love this one ! Solved it by using the fact that a miner removes a bit of terrain above his head, so a single miner can both free the crowd and open the way to exit, nice ! I guess one can also extend the miner with bridges on the right side.

9 : As compicated is it looks ! Awful turn around tricks everywhere, I must say I do not like this one very much, but I got the talismans nonetheless.

10 : Also hard to execute, no real thinking involved I guess. I managed the talisman by going the counter-intuitive right route.

11 : Really clever puzzle ! I spent about 4 days thinking about it to solve, it took me some much time to find how to control the crowd and use this extra basher. When you look at the solution, it looks obvious though, the mark of great levels !

12 : This one was also very hard to me, both because of time limit and crowd control. Hint : the stairs are not the same between the pillars...

13 : Nice puzzle and easier than the previous one in my opinion. Or maybe the previous one served as a training for this one ?

14 : I think I backrouted this one with basher-blocker trick. I end up with lots of skills left.

15 : Long and exhausting level, this Super Lemmings is really strong ! I did not try the talismans as I was kind of worn after the clear, sorry.

16 : Awful Group Control ! Achieving compression with walkers only is definitely hard. And the hidden Cameleon at the end is pure evil !

17 : Really nice puzzle, pure Lemmings style. One of my favorite in the pack, congrats.

18 : This one was really hard to me too, until I let the pionneer escape to the left instead of the right. This remains a very good level, builderless and need to control that zombie correctly.
I can maybe see how to solve faster for the timed talisman, but have absolutely not idea on how to solve with a single jumper and all the destructive skills though ! I'd be curious to see a solution for this talisman is someone has one.

19 : I think I have another backroute here since I saved 25/23 with many skills left. I used basher cancelled by shimmier to gain height and save many builder I guess.

20 : Interesting level with 99RR, so all happens at the beginning. Maybe another backroute as I save many skills again ?

21  : Once again hard to execute. I did not try the talisman as I do not like the miner-cancels-miner trick. Though this level definitely teaches you how to do this correctly !

22 : I found this one easy with all those super powerfull skills like cloners and walkers. Another backroute ?

23 : Hard to execute, so much that I ended up making a little paper frame showing a cloned laserer. Then I put the frame on my screen at many different place to see how I could save 2 or more blockers at once. In the end the 1.15 time limit is not that hard.

24 : Tough one, but satisfying when you pull it out. I did not use the blocker, and I think its presence made me loose much time. I'd say my solution not using it is more straightforward.

25 : Good puzzle, hard to spot what to do with this crowd.

26 : Tough one, the chains are not symmetrical ! Once you spot this, it becomes easier. I could not get the timed talisman though, I can not prevent my worker to make an unwanted back and forth way...

27 : Definitely a favorite of mine ! Straight lemmings puzzle solvable with not that muck tricks. All skills used to their full extent, especially all those miners that seem useless at first in this setting. Great level.

28 : Hard to execute zig-zag builder with blockers, freeing lemmings at the correct timing is tough.

29 : Favorite of mine too ! The original level was hard too, but this one is climax. I love it, thank you.

30 : Many skills given, but managing time is the hardest here. I'm not sure I could save 5 more seconds for the talisman.