Most inspirational / revolutionary levels

[Crane]

So after noticing a commonality that's appeared in a couple of levels in Contest #30, I've come to realise that a level sometimes becomes a stand-out inspiration for future design.  It's not necessarily the best level (sometimes it's not even nominated for Level of the Year, assuming its age is not so old that it precedes NeoLemmix) but something about it inspires other creators to add elements of its design into their own levels.

So I'm curious... what levels do you think are truly stand-out in this regard?

To start, I'll name one of the originals:
- Mayhem 3: "It's hero time!".  The original 1-of-everything puzzle really sang to custom level creators!  I think virtually everyone has made one of these at some point in time.

[Proxima]

Other particularly inspirational levels from the originals:

Taxing 6 "Compression Method 1" -- I mean partly the compression method itself, which often appears as part of a more complex solution, but more the fact that this was one of the purest examples of an "aha" moment where you are completely stumped, and then you have one insight and everything makes sense -- which designers often strive for and don't always achieve!

Mayhem 20 "No added colours or lemmings" -- The stand-out example of a pure puzzle level that has only one solution (except, apparently, in NeoLemmix, but even there, it took years for any skill saves to be found!)

Genesis Sunsoft 29 "I am A. T." -- the original digger staircase level is another one with imitations, variations and sequels in many packs.

From custom levels:

Lemmings Plus I, Psycho 28 "To the End!" -- the level that gives you 20 of everything except builders, forcing you to use several tricks to turn around and gain height so as to get around gaps that can't be crossed without builders.

MazuLems Level 9 "Holy Cow!" -- the originator (as far as I know) of the now-standard trick of placing bridges between two obstacles so a single basher or miner can keep going and cut through both of them. The trick is also pretty well hidden on this level, so it's not immediately obvious that this is the trick used even if you have seen it before!

[namida]

MazuLems Level 9 "Holy Cow!" -- the originator (as far as I know) of the now-standard trick of placing bridges between two obstacles so a single basher or miner can keep going and cut through both of them. The trick is also pretty well hidden on this level, so it's not immediately obvious that this is the trick used even if you have seen it before!

This is a really good example tbh. That particular trick is very commonplace nowdays, but it was absolutely amazing at the time.