Quartet 1 -
I forgot to pack! Nice level to start off the rank! Not very hard but at the same time not trivial at all. Even with the very limited skillset, it's still an open-ended level. How did you get the design to look the way it does here? I especially love the touch of the moon in the night sky setting here!
Quartet 2 -
A shell game Another great level. I thought this was going to take a while, but I surprisingly solved this one quickly. Nicely done with the snails here!

The Snow tileset is certainly one of the harder tilesets to work with, but you did great with it.
Quartet 3 -
Permission for takeoff Nice 1-of-everything level in 6 skillset types. I didn't think my solution would work, especially in regards with how I used the digger, but it did, so good enough for me! I checked your intended solution, and I think I like yours better despite how our separate solutions are kind of about the same difficulty.
Quartet 4 -
Give me a plaice to stand... I really like this one. It reminds me so much of "Distract Them" from Lemmings Reunion, as it uses a similar tactic of keeping the crowd busy while a worker lemming goes on ahead to forge the path before they get in danger. Nicely done, and the Rock tileset from ONML is one of my favorites, although Bubble is my top favorite from ONML.
Quartet 5 -
Simple Geometry Another great level, although my solution is much different but as you have said acceptable. I like how you did the geometric shapes on this level

Quartet 6 -
In the ancient glade Very nice design here! Deceptively difficult, although as can be seen in the LP I especially struggled with the exit area. However, it was due to me overlooking something very simple

It is interesting how I managed to save up more skills than your solution, but well, anything that solves the level when I'm playing is good enough for me

Quartet 7 -
Is the beach day cancelled then? Another one of my favorites of the rank! The hardest part was definitely saving the builder who makes the splatform for the others, as well as how to make sure everyone is safe and no one turns back to the left at the start to die. Very nice solution here. Also checked your solution here, and I can't believe I didn't spot that with building over the first digger pit

I like the meteor touch you put in the level here

Quartet 8 -
No repairs necessary Somewhat hard but another great one. The start was certainly the hardest, and I was a dummy about how to make a turnaround for everyone so that no one goes out to the left to die, especially for the climbers. My solution uses timing so that someone beats the worker lemming to block so that he just turns back to the exit. Checked your solution, and I definitely like it better than mine.
Quartet 9 -
Broken warpgate Ah, a Bubble level, which happens to be my top favorite tileset of ONML. I just love all things bubbles. Nice solution, but very unfortunate that I fell victim to trying to make my solution work and it failing everytime no matter how much or little I kept adjusting the blocker position. I eventually got it to work, but as can be seen in your solution no timing is needed at all. I'm still impressed by the solution due to the compression that's required in order to minimize losses to the trap. Nice job here.
Quartet 10 -
Next day delivery Looks intimidating and hence very hard, but it wasn't as bad as I thought. The hardest part of the level would certainly be getting through many of the obstacles with the very limited skillset, especially the digging destructive skills. That was really nice with the truck that has the word Lem on it

Once again, love the touch of the moon on the very far right of the level.
Quartet 11 -
Castle on the coast I thought this one was hard, especially with saving the non-climber and releasing the pre-placed lemming, but that's because I overcomplicated the solution

I definitely like both of your solutions better than mine. I could had avoided the very fiddly block to turn the basher around but the blocker gets released by having the non-climber turn around in the basher tunnel and have him build instead, as the climbers can get back up themselves. Now I'm starting to think that this behavior should be patched out, as I didn't think too much of it at first, but the more I think about it, the more I start to hate it.
Quartet 12 -
/The n-body problem The most visually impressive level IMO, even if it's quite bare for the most part. You did great with depicting the planets here, especially the Earth!

I can live with your depiction of the bubble planet, as it's my favorite tileset of ONML anyway

Another level that looks very hard but it's not too bad at all. It's open-ended for the most part.
Quartet 13 -
The long ride home Backroute, as you have mentioned. I checked your solution, and indeed I did think about doing what you did with the basher and miner, I just couldn't think about how to achieve it. Not only was the miner unintended, but the way I got up the level too

Even then, nothing that steel or OWAs to prevent my miner usage in order to force the intended solution better.
Quartet 14 -
On the button Deceivingly hard level which isn't too easy to work out what needs to happen. My solution spares a blocker, though as you noted it's interesting how the blockers can be used on this level and still produce different solutions. Here, I placed a blocker close to the right edge so that a climber can still get past it from underneath. I also used it to turn a digger, as well as a digger cancelling another digger. This is also a visually impressive level. I especially love how you depicted the four different suits of a deck of playing cards. Are those supposed to be poker chips or the cards themselves where the lemmings start on?
Quartet 15 -
Can't stand the heat? Very hard one, where there seems to be way more obstacles to get through than you have digging destructive skills and hence it's very easy to run short on skills. Not easy to know how to navigate the level. Very impressive on the visuals here. I love how various parts of the kitchen are depicted here, such as the sink and frying pans over fire and a pot with boiling water. Nicely done here!
Quartet 16 -
A night on the town Another very hard one but another favorite of mine in terms of the puzzle and visual design, so looks like we're in agreement here! The start was especially hard to figure out, and I tried various things there, only to have the solution fail because I won't have enough skills to finish the level later. It was also very hard to figure out where and how to get through the OWW. In the end, it was a lot of fun to play and figure out how to solve the level. I especially love how it needs to be a non-climber to do the final staircase to the exit. Indeed, at one point I thought I had the level solved, except for the problem where the climber would turn back to the left after building and die. Here my solution relied on timing in order for the non-climber to carry the rest of the work before the climber arrived and got into danger. This took some time to get the timing right, but it was really down to bashing at the start earlier so that the climber is slowed even more due to how much terrain he has to climb.
Quartet 17 -
Phantom breakout This right here earns a nomination from me for LOTY!

The solution is really good and is one of the best levels I have played and solved and have seen in a very long time. The start is the hardest part, figuring out how to get the two non-neutrals to go on ahead without the neutrals being able to follow them. I've seen a United level that uses the trick of raising a wall high enough so that no one can step out, but that is from the same direction as the builder. Here it's from the other side, but same logic applies. Once you figure this out, the rest of the level is easy. It seems that Armani is in agreement with me that this is the hardest level of the entire pack. Nice job, Apjjm!

Quartet 18 -
Let's try beach day tomorrow! As noted, parts of the designs of all the previous levels of the rank make an appearance here for the final level of the rank. Even though this is open-ended, I still had so much fun playing and solving the level

Very nice level to round off the rank and main part of the pack!