Alpha 2 : first clear I went for killing all Zombies with the trap up there. It was satisfying to watch them get squished
Talisman took much more time, hard to imagine a way to trap the zombies and escape at the same time !

Alpha 4 : I could do the clean compression required fo the talisman without using the RR. I guess with the given miners and how you can adjust them, you can just create a compression pit which has the correct width for them to compress cleanly. The walker and empty bashers skills allowed to perfect the compression and loose only 1 lemming to the trap.

Alpha 5 : how hard is this one ! Normal clear is manageable, but talisman requires to not loose a single lemming and this is another story.
In the end I used the "take it as it comes" approach. Meaning I did not make many plans ahead, but just used "optimal" methods when they were needed to progress through the level.
Twice I used the platform bricks that go through terrain when the platformer gets stopped by a very thin wall. This reminded of some Armani's levels which used that too, crazy.
In the end I did not have that much trouble getting a close enough crowd to trap them with the last platformer.
This level certainly taught me a lot about sliders, jumpers, platformers. Thank you !

Alpha 6 : what a nice level ! It took me some time to understand what needed to be done, and much more time to do it in under 1m30s for the talisman. "Quick Sort" is definitely the correct name for this talisman ; can you imagine a "Bubble Sort" level tan x dx ?
As everyone, the hardest part was to sort out the floaters from the swimmers. I did it using very close compression, plus the very small delay given to floaters when they open their umbrella.
In the end I think I have a somehow clean talisman solution. Then I looked at Ichotolot's solution to compare and say proudly (no pun intended Icho  ) : your solution is a total mess ! Mine is cleaner 

Alpha 8 : I love this level ! I also learned a lot about laserers here, and could do a save all.

Alpha 9 : kind of easier than the previous level to me, same mechanics used.

Alpha 10 : now this is a masterpiece ! First clear I killed the leftmost zombies, and avoided the right ones. It looked natural but used a lot of resources.
Second clear for the talisman gave a real awe moment :  realization that I could extend that basher all the way through to free both the right and left crowd !
But then putting that extension in place was really tough because so many things have to be taken into account : platform all the way through at the correct height, leave a zombie alive somewhere so that the basher turns into one and does not enter the exit, make sure you have enough resources to free all 3 crowds at the end.
My solution works, and use all resources.
Then I watched Icho's solution for the talisman, it is mainly the same one but is more insane with the basher going down some bridges, and the flow of builders in a hurry at the end to build the necessary bridges. Crazy !
Congratulations for this brilliant level.

Espilon 2 The problem is quite clear after some tries : if you build from the platform then the lems splat before the exir. If you build from the floor lower, the splatform is not high enough. So what to do ??
I love this solution

Espilon 3 I found this one very hard, mainly the part when one needs to avoid the splat by tweaking the diggers. Maybe there is an easier solution.

Espilon 5 Yes, the worker can do everything. I'd think this solution is backrtoute, since it is a very straightforward level this way.

Espilon 6 An occurence of "trigger the thing that will unblock the blockers, before the blockers are even set". Nicely done.

Espilon 7 Roadblock for some days to me. Dolly Dimple bridge on the left side is ok. But the blocker freed by the bomber on this thin floor of the bridges eluded me for a long time. Hard to execute !

Espilon 8 Favorite of kaywhyn, and hard talisman. Discussion above.

Espilon 9 The solution appears quite quick here, but the timer is the issue.
And now appears a very rare case : timed level where if you free the crowd too early, you'll actually loose to time ! Great design !

Espilon 10 Very good finisher for the rank. I love how it is called "what have we learned so far ?" and indeed uses many techniques already seen : Dolly Dimple bridge, mid-air bomber. Plus a blocker used as a waiter, I love them. Brilliant level.

Delta 1 The first level I actually played from the pack, due to my weird habit of playing the ranks backward. And that was a tough start ! I finally got that needed half-turn by having 2 very close lemmings : when one of them becomes a stoner mid-air, the second one gets trapped in the stone and turns. Wow !

Delta 4 Another case of basher extension with platformer. Same method that I used in Alpha 10, but way easier to set up here than in Alpha.

Delta 6 Intimidating at first due to the lack of constructive. Thoug as Icho said, once you see how to do it, it is not that hard to execute. Taught me a lot about stackers too, nice.

Delta 9 Tough one. If like me you want to keep a builder to get above the trap and be able to get over the last gap with an isolated worker, you'll have a very hard time !
Just bomb the trap, and accept to build the last gap while some lems are drowning looks easier.
For some tries I ended up a lemming short of requirement, then I had to willingly cut the shrugger animations in some builder to save some frames and reach the required number.

Delta 10 Not my favorite level I must say. This is the kind of level in which you have to experiement to see what does work and what does not. No real puzzle involved, just trial and error.
After many tries I thought I was about to give up, when I finally could go up that last step with a mid-air stoner triggered right before a builder. This allowed to go higher than the builder itself, and that was done ! I was relieved.

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.