So... what's the hardest level you can make with only one type of skill?

[Nortaneous]

Wow, I had to rack my brains a fair bit before I remembered this (it was some time ago http://www.lemmingsforums.com/Smileys/lemmings/wink.gif" alt=";)" title="Wink" class="smiley" />), but that would be my remade version of "Singular Squish". There's really not much to that one, since the miner placements are all equally spaced, unless for some reason you change the release rate during play. Even if you added more lemmings, it wouldn't add to the difficulty in terms of finding a solution, just executing it would be more tedious.

Equally spaced? Did the intended solution involve the steel bits? I just waited for them to turn around, made the first one a miner at the part where you mine down to get through the horizontal barrier thing, and then had the rest of them mine in that same mineshaft.

[Clam]

Ooh... that could work, I guess. I seem to recall testing that, but I don't think I managed to actually solve it that way. Maybe I should make that bit of the floor thinner, so you can't get all the lemmings to mine together (they'd just take a swing and fall through instead). Yes, the intended solution uses the steel to turn the lemmings around.

[geoo]

I've taken a shot at making a bomber-only level that doesn't solely rely on bomber timing to create the difficulty. I guess it's rather easy to figure, but hopefully not entirely trivial.

I remember a well made but fairly hard Cheapo pack that got posted here a while back (forgot who made it, though) that had a dirt set level with nothing but bashers that was not at all trivial and actually quite fun. Used the non-even terrain of the set very, very well.

What you're referring to might be the pack 'Why bother?' by the Purpletraitor (and drumnbach?), specifically the level 'Mount Bashmore'. "A while back" is quite an understatement though.
That reminds me though that I've still got to have a thorough play-through of this pack, because back in the day these levels still seemed pretty daunting to me.

EDIT: In this pack, there's also "...but, but, but...?!?!", a builder-only level.