Heinous 1 -
Ascension Somewhat hard level but still a good one to start off the rank. This level kind of reminds me of that one Clammings level also in the Crystal tileset which has a similar idea of releasing blockers with bombers, although I think it also uses bashers to do so too. That level is harder IMO. I had the feeling that one was supposed to bomb to make a climber friendly wall, but here I placed blockers at the very edge at the very top which still allowed the climbers to get by them.
Heinous 2 -
Ballad of the Flexible Lemming Easier than the previous level, and one that I certainly remember from Lemmini. I have a basher leftover

Heinous 3 -
Honey, I Shrunk the Levels Again Disjoint union level consisting of levels from the OL: the repeats of Now use climbers and miners, Bitter Lemming, and We are now at LEMCON 1, and Stepping Stones. It's just a matter of using the solution on the repeats, although it's still not a complete cakewalk. In one of my attempts I was a basher short and was looking to see where I could save one, until I realized the bomber I had spare could be used as a substitute, which of course can only be effectively used as one on thin enough walls to blow through with just one due to the very limited range. It was also hard to see that you have to accept losses in the Poles Apart mini level until the builder builds to get over land.
Heinous 4 -
The Bricks of Wrath I'm sure this is a backroute. I originally tried doing things in the long basher tunnel to the right, which I'm sure is intended, but I couldn't get a builder to build over the miner hole in the floor so that the others do not go out to the right and drown in the water. And now that I've looked at it again, I think I know how it's supposed to be done

Good level nevertheless!
Heinous 5 -
Get Behind me Satan Somewhat hard, but only because I tend to have a hard time with zombie levels. It was not easy to figure out how to avoid the zombies at all. I like how one of them goes over the wall on the far right while you have to figure out a way to safely get to the bottom OWW to allow the climber through to get to the exit. This is a pretty good puzzle!
Heinous 6 -
Eye of the Needle I remember this one and how really good it is! Thus it's one of my favorites too. Its solution is very similar to "Hard to Port," plus bashing through the OWW to release the crowd.
Heinous 7 -
Take A Giant Nose Dive part 2 I think I like this one more than the first part. Nearly similar solution, except there's no wall to build to at the bottom to turn the worker around to climb into the bomber hole to make the splatform. The hardest part to see for players, I think, is to block close enough to the wall so that the splatform serves another purpose, and that is to build over the blocker. Awesome level and solution!

I remember this from Lemmini, although if I'm not mistaken this level is the one used for that pack?
Heinous 8 -
The Gambit Hard one and one which I struggled longer than I thought I would. I initially tried a very fiddly and timing heavy solution, but I thankfully realized it wasn't necessary and abandoned it at some point. Even after discarding that, it still took a while because I couldn't figure out how to stop the climber(s) from getting into danger after the path was ready. I remember this from Lemmini, and I don't recall struggling with the level too much, although I could be remembering wrong.
Heinous 9 -
Presto Chango part 2 Near repeat except this one is much harder than the original. I definitely struggled here. Looks so simple but it's deceptively tough. I think this is the one I remember from Lemmini maybe minus the ketchup wheel trap. My solution feels like a cheesy backroute, although thinking about it it might be intended after all. I think the addition of the ketchup wheel trap is what makes going up the far left side at the bottom an impossibility because of how you need to spend a builder to get past it. Once you do that, a builder alone won't be enough.
Heinous 10 -
Now Use Builders and Blockers! Even with just those two skill types mentioned in the title, this one was another deceptively hard level. It might seem you have a lot of builders, but you cannot waste any at all. It's not easy to see the most efficient way to build on either side, as well as to see the tricks needed, though to be fair they're kind of obscure themselves even though one is somewhat well known to the community. This is definitely for sure to catch a lot of people off guard. Dolly Dimple trick on the left side, building to add another pixel of height on top of an already built staircase so that another builder to build into it to turn around and hence can kind of be thought as a variation on the former builder trick. In either case, the blockers are used to release the crowd and get them going in the route to the exit. Very nice puzzle, but yea, very hard one.
Heinous 11 -
The Cliffs of Insanity (part 2) Another repeat, but this time without builders. Certainly harder than the original, but not a whole lot. I ran into problems because I kept trying to save the basher. I initially used the very fiddly basher cancelling trick with a blocker where the latter gets released but the basher turns around and gets cancelled, but as I don't like this solution I instead went back to find another solution that doesn't use it. Turns out that not paying close enough attention to the save requirement got me into trouble here, as it is not necessary to save the basher at all. Now that I think about it, I think I remember this version from Lemmini, because I vaguely remember using some timing to get everyone past the basher tunnel in time before they won't be able to exit anymore. Very nice compression puzzle!
Heinous 12 -
Hook, Line and Sinker Excellent level! I think I remember this from Lemmini too. I really like the part of using the blocker to isolate two lemmings, one of which floats down to build to the exit as well as build to create a landing platform for the others, and the other one to dig at the right edge in order to make a safe drop for the others so they don't splat. Finally releasing everyone, including the blocker, with a miner so they can drop into the digger pit.
Heinous 13 -
Off the Deep End part 2 Another repeat/part 2, except I think this might be a bad backroute because of how I have a lot of skills leftover. Surely it's not supposed to be as easy as climb, build, build to stop the climber from going up the far left wall, and then bash the crowd out? I think it's certain that the right exit cannot be used this time, as there's no floater to get down safely at the start.
Heinous 14 -
The Lemming Who Japed Another really great level/puzzle and one that I remember from Lemmini. Very good 2-lemming level. It's still not an easy level IMO. I like how the digger pit is to delay the other lemming long enough so that the digger has enough time to make landing platform for the climber and so he builds over land. Also how the athlete goes through the bottom while the non-athlete doesn't. The athlete proceeds to mine to prepare the way for the other one. Even after you have the route all figured out, you must make sure the athlete doesn't get himself into danger by going out the left later.
Heinous 15 -
Tinker Tailor Soldier Lemming revisited I believe this is the version I remember from Lemmini, as I vaguely remember digging to delay the crowd, as well as to send a climber out from the pit. Certainly the hardest out of the other two with nearly identical layouts, but the solution is really good here. Because of the protruding overhang on the left side of the huge wall in the middle, there's no possibility of sending out a climber from below this time. It does need to be timed so the climber mines to turn the non-climber around so that he can mine the crowd out contained between the walls. Unlike the others, I think I can see the need for the locked RR here in order to avoid frustration. Even then, it can definitely be done without

Heinous 16 -
The Lem Lies Down on Broadway I certainly remember this level from Lemmini. Despite having not played this in a long time, it's clear that extending the basher with builders is needed here. I think I remember the medieval theme from L2 playing on this level.
Heinous 17 -
That Figures I think this might be the version I remember on Lemmini, although I think this one used the Dolly Dimple builder trick instead? I do remember a Marble level using it and where I learned that trick but because I didn't see to use it for some time it took me a while before I solved it. I like the solution here too, especially since I love the shimmier skill. In addition, that was a very nice use of a builder to stop the climber(s) from going out the far right and into the shredder trap.
Heinous 18 -
Over the Hump I also remember this one. I love how the climbers are used as delays to give the builder enough time to build to the exit. I also like the releasing the right entrance with a basher after mining. It's also a bit more complicated than that, since you need to do so before you run out of climbers. Here, I don't think my solution would work, since if I'm not mistaken you had 1 minute timer, and I used only slightly more time than that. However, that's easily fixable, since it's just making the basher tunnel shorter, or just build so that the worker doesn't turn around.
Heinous 19 -
Lemming on the Rocks Easy level and one I remember from Lemmini. I love the stalling tactics here, with using a miner to give the worker enough time to build to the exit, as well as bashing to release a blocker, who contains the others between him and the miner tunnel. The timing can be tight, but it's very satisfying seeing everything come together and when it all works out.
Heinous 20 -
Slip Up Yet another one I remember from Lemmini. Slightly harder than the previous, but that's because of a trick needed here. I also remember struggling when I first played this level years ago. Very nice use of a basher to punch a tiny hall in the pillar so that climbers can get into it later to bash. Finally, timing two workers so that the other gets by the first builder in order to patch up the tiny gap before the exit. Overall, an excellent puzzle!

Heinous 21 -
Between a Rock and Hard Place I vaguely recall seeing this in the Lemmini version. Now this is a much harder and far better and worthy replacement for Highland Fling from the Havoc rank of ONML, which the community pretty much considers easy for the final rank of the game. You certainly did that level justice here

The 99RR is what increases the challenge significantly, as well as how there's two trapdoors. I struggled here longer than I thought I would, but that's because I once again failed to see the sealing off a basher tunnel with a builder, which I remember was the same thing that did me in in a Lemmings Migration level in the second rank. However, this can be frustrating to pull off because the area to do so is very small.
Heinous 22 -
Rainy Day Lemmings #12 and 35 Repeat of Friendly 2, except there are zombies here in addition to the skillset change. Definitely harder because of the zombies and also hard puzzle because of the pickups. It took me a while to see how the pickups are used in the solution. I used some timing to get another climber to arrive at the miner tunnel early enough in order to bash through to the exit. This solution seems intended, although I can't help but think there's an easier solution.
Heinous 23 -
Narbacular Drop I remember this one from Lemmini and certainly a hard one when I first played it years ago. I got the solution down quick, but it was frustrating because of how two kept splatting after dropping out to the left in the digger pit. I don't know if there's any other way that will work besides maxing out the RR right away at the start. I kind of remember not needing to do so when I solved it before. Great puzzle here, and certainly worthy of the Heinous rank!
Heinous 24 -
The Whispering Wind Another near identical repeat, and definitely harder than the original it's based on. I think this is the version I remember from Lemmini, as I'm certain I recall the splatform needed the way it is in the solution here. That was the hardest to see in this level: How the builders are used. I ran into problems due to not realizing the connection with the climbers of those who get contained in the pit at the top left. Overall, a very good puzzle and one which was very satisfying to solve and figure out again after so long. Not to mention it's also in my favorite ONML tileset!

Heinous 25 -
The Great Escape I think I remember this from Lemmini, as I do recall a level where you have to build from both sides of the vine swamp. However, this is a zombie level, and as mentioned before I tend to have a hard time solving these levels. I definitely have seen a lot of great zombie levels when they're used well, but I tend to hate these in contrast to some other features that got culled, such as ghosts. I actually liked this gimmick when it existed.
As for the solution, I was a dummy for a very long time with the start, as well as dealing with the zombie at the bottom. It took a long time to see that one must build the right half first and that is how you lose the zombie. I also didn't think making the top zombie splat was possible because I thought some lemmings from the top would also spill out to the left and splat, but turns out it's possible with very careful placement of the digger so that the zombie doesn't land on steel before falling the rest of the way and hence surviving. The other hard part is bombing the blocker so that you release one lemming to build the left half to seal off the rest of the gap, but the gap needs to be big enough to give him enough time to do so. Brilliant!

This was quite a nice puzzle, and the level is in yet another ONML tileset that I like.
Heinous 26 -
Oblique Strateegy This level I vaguely recall being in the Lemmini version, although again maybe I'm remembering wrong. Quick one, although there was still the annoyance of figuring out how to stop the climber from getting himself into danger later on when he can go out the far left side. Also with getting everyone at the top contained in the digger pit so they can survive the drop to the splatform. Dolly Dimple builder trick is needed here in order to get up to the top of the level, as well as to still allow the bottom entrance from accessing the exit later.
Heinous 27 -
Five Easy Steps... Another really good level that didn't take too long. I love the solution here a lot, particularly since it uses a trick that isn't seen too much in custom levels: Mining out the builder staircase in order to make way for climbers from below later, which is required in "No added colours or lemmings." I was a dummy here though in thinking that the climbers/floaters needed to fall past the miner tunnel, but the builder staircase to seal it off is what will help them get up later. Nice job with this level!

Heinous 28 -
General Tsao's Lemming To finish off the pack is a very old contest level of mobius,' one of his first if I'm not mistaken. I've already played and solved this level when I was doing my off-camera playthrough of all past contest levels last year. However, I stopped after about two contests and haven't really done anything with it since, so I should get back to doing it again soon. I certainly remember this one being hard, which surprised me considering the author. It's not to say that mobius doesn't have his fair share of hard levels, but rather if you're familiar with how he claims his Mobilems pack is on the easier side then you can easily be led into a false sense of the difficulty with his single levels too. This level does a great job of making you think certain skills have to go here and there, such as bashing the wall in which you start on top of. Turns out that you can almost get the level solved, but it doesn't quite work. Instead, it was hard to see that you can afford to use the basher for the far left and still being able to solve the level. In particular, digging down the right edge of the wall and then mining both the crowd and the blocker free was quite hard to see. Although this might seem disastrous with everyone going out to the right, you can still release the climbers to go to the far left exit later. At the same time, it's easy to see that bashing on the far left is the most efficient, as you don't need to do anything else other than a digger at the top on the far right edge of the pillar. I really like the puzzle here, and certainly a great one for mobius to make his foray into level designing.
To be fair, it's been a while since I've played this level and hence I have forgotten how it is solved. Of course, it doesn't matter, as eventually I can figure out the solution again. It's great exercise for the brain anyway