And whilst we're on the subject, here's a new trick for you - since lem recolouring for athletes is kept active in Classic Mode, assign a Floater or some other permaskill to one of the lemmings in a group, and this lemming will now visually stand out from the crowd! From there, it's very easy to see which direction that lemming is facing in, and whereabouts they are!

Does SLX prioritise assignment to floater-walkers over plain walkers?

I really like those! Neato! Question, I know, I always have one But is it important at all to have the titles with capital letters in them or is it fine without all words being in capitals?

That's entirely a matter of personal taste. The original games are notoriously inconsistent with capitalisation: most levels either just capitalise the first word, especially if the title is a sentence ("Only floaters can survive this") or follow "title case" with important words capitalised ("Curse of the Pharaohs"). But then some levels capitalise every word ("Livin' On The Edge") or capitalise "Lemming" and nothing else. One level is in all lower-case ("worra lorra lemmings"), a few are in all caps, and ONML has titles with random capital letters inside the words ("LeMming ToMato KetchUp fAcility"), especially on timed bomber levels.

Something that has often worked for me is to start with a relatively complex terrain -- sometimes from an existing level -- and find a solution, either for the original save requirement or for 100%, trying to keep skill usage balanced (at most N of each for a suitable value of N) and in particular to minimise high-value skills like builders and miners. Then make a copy, trim the skillset to what you used in your solution, or N of everything, or a patterned skillset like 3-2-3-2... and you have a level!

Of course, if you are doing this based on an existing level, keep in mind that you can modify the terrain as well. For instance, in "Rhapsody in Blue", my 2-of-each copy of Insane Steve's "Rhapsody", I cut out the pipes along the top platform, because it would have required extra destructive skills to get past them, ruining the 2-of-each pattern.

https://supersonic.com/learn/blog/difficulty-curves/

If player criticism had always been heard this readily, perhaps Radiation and Slowfreeze would never have been culled from NeoLemmix in the first place

You seem to forget that these culls were decided on by forum discussion. Sure, Nepster as (then) project leader was the one who actually made the decision, but that was after opening the decisions to public criticism -- which is why the disarmer was kept, for example. For slowfreeze, there were a couple of dissenting voices, but not enough to outweigh the arguments in favour of culling and the number of people who contributed to the discussion and supported it.

And believe me, those of us who supported the cull haven't disappeared; we just don't keep posting about it now that it's long since decided. But now that NL has moved into new-formats with its much better quality-of-life features, I've completed several packs and look forward to playing more when I have time. And every time I select a pack with the intention of playing all the way through it, I'm glad that I won't have to suffer through radiation and slowfreeze levels.

As for backgrounds, I hope these remain available as they are

I think there is a confusion here. WillLem is talking about the "background" object type, not backgrounds!

When talking about contemporary level design, don't forget to mention one of the biggest differences between modern and old engines: the glitches are fixed! Indeed, this was the big difference between the LPII engine (which became NeoLemmix) and old Lemmix; all the convenience features (except untimed bombers) came later.

In the Cheapo/CustLemm days, it was just taken for granted that glitches were part of the game, and glitch solutions were considered legitimate backroutes and had to be proofed against. (Cheapo, incidentally, had perfect steel long before NL, and I don't think it had sliding, but it had many glitches of its own.) It was especially frustrating because those who investigated glitches (mostly ccexplore but also Clam, geoo, tseug and others) kept them semi-secret, usually announcing challenge results using the glitches instead of explaining them.

It's weird now to look back and think how different the culture was in those days, and to remember that back then, we had no idea about how much things would change

I suggested the arrow version on the basis that it might be better than the lemmings walking in and out of frame (because with the latter, you just see blue and grey alternating, so it's not really clear which is "before" and which "after").

But I still favour a single-lemming static image over either. A neutral lemming for the neutraliser, a normal lemming for the deneutraliser.

The only thing that's been said against that suggestion is that the deneutraliser could be mistaken for a "walker assigner". I don't think we have to take that objection very seriously, because that doesn't make sense as a gadget in any case.

Sorry to have taken so long to follow this up. Here's a replay showing how 8/10 can be saved with a variation of the intended solution.

The variation in question:

If the terrain fix works, then we can leave it, but this solution is here if we need to refer to it later

EDIT: Had a look at Forestidia's solution (first post of this topic). This might be preventable by making the first wall thicker; I'll have to look into this another time.