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.

Migraine 5 We're Coming Home : I have a climber left, did not find what to do with it. Setting up the digger stairs and freeing the crowd at the end in time with the suicidal basher was very hard. So I think I'm missing something with this extra climber

I used the single miner to destroy terrain both under and above him.

I used a basher canceled with a blocker in the central triangle.

Typical exemple of taking the long way with the pioneer to save the "crowd"

Stacker cancel : assign a stacker at the exact same place than a previous stacker, or than a currently working stacker. This way the last assigned stacker will cancel after trying to set one brick over the already existing stack, and most importantly he will turn around.
I used this to contain and compress the crowd at the beginning, and to prevent the last climber from climbing the stacks leading to the exit.

Prepare 7 Flower Power. I had a surprisingly hard time containing the crowd and pushing the button here. I must have used a very suboptimal method, but it worked in the end !

Prepare 10 Construction Function. Very nice design on this one. I had a fun time figuring out a route from those thin diagonal floors, and went via some small holes here and there.

Prepare 16 Caught In Liminal Space Great design again !  It reminds me of the game Castlevania : Symphony Of The Night, mainly on PS1 and Saturn consoles if anyone is familiar with the game. The whole game is set up in a giant castle you have to explore. And where you think you're finally done with it and beat the final boss comes a twist :

Spoiler

You have to go through the whole castle again but it is reversed upside down, opening whole new paths and ways to explore !

So yeah, having reversed elements in here reminded me of that tremendous game.

Nuisance 6 Mesmerizing 1st level by Armani, I was not even scared ! And it went smoothly 

Nuisance 7 Mirror World 2nd level by Armani, I was not even scared, and I should have been ! See discussion above.

Nuisance 8 Hoopin' on the groove line I had fun jumping here and there. A bit disappointed by the end part tbh. Maybe I backrouted it and the intended solution is somehow funnier ?

Nuisance 8 In The Rear With The Gear Not a very big fan of the level tbh. One quickly understands what needs to be done, and after that there is no thinking involved.  I salute the original idea and the beautiful design.
And most of all I salute the reference to that Sergent in the Full Metal Jacket movie, that very one who tells Joker he better stays "In The Rear With The Gear".
Now please make a level named "Lem has guts, and guts is enough".

Nuisance 14 Sugar Free Lemming Aid I spent so much time on this one ! For some reason I tried to used the downer tree branch. Must have realized sooner that this is not the correct way because it is hard to reach that is used up almost all my skills.

Nuisance 19 The Aquatic Ruins Very nice design again, where you have to let a lemming wander around and make the work in a very precise order and fashion. Making sure the crowd does not splat at the end was not that easy, maybe I missed something.

Nuisance 20 The Choosen One See discussion above, a real trip for my brain.