Don't turn around!

[Proxima]

In the big challenges thread, someone posted this challenge for Fun 1: 100% with one digger and no lemmings bouncing off a left wall. To generalise this as much as possible (levels with exit further left than entrance, multiple exits or entrances, Cheapo / Lix levels with left-facing entrances...) I decided to rewrite the condition as follows: Find all levels that can be solved with no individual lemming turning round more than once.

Here's the current list for Original Lemmings and ONML:

FUN 1, 2, 5–28, 30 (100%: 1, 2, 5, 7–11, 13, 14, 16, 17, 19–21, 24–27, 30)
TRICKY 1–7, 9–13, 15, 17–22, 25, 26, 28, 29 (100%: 1–6, 9, 12, 13, 19, 21, 26, 28, 29)
TAXING 2, 5, 9, 10, 12, 16–20, 22, 24, 25, 27, 28, 30 (100%: 2, 9, 10, 20, 22, 24, 30)
MAYHEM 4, 10–13, 15, 25, 26, 28, 30 (100%: 4, 11–13, 25, 28)

TAME all 100%
CRAZY 1, 3, 5, 9, 11–13, 15, 16, 18–20 (100%: 1, 5, 9, 15, 16, 20)
WILD 1–3, 6, 8, 10, 15, 17, 18, 20 (100%: 6, 8, 17, 20)
WICKED 1, 3–8, 14, 16, 17 (100%: 3, 5, 14)
HAVOC 3, 4, 9, 10, 12 (100%: all except 10)

Fun 11 is particularly fun and Taxing 28 is rather a neat puzzle, as it doesn't look possible for the challenge at first sight.

It has to be said, this is one of the more sadistic Lemmings challenges -- for instance, on Fun 14, you'll never make it if you try multi-bashing, so the way to fulfil the condition is to have the lemmings who turn round kill themselves by bashing through a left wall of the structure into the water!

[mobius]

that's a good idea! but I'm not exactly sure what you mean.

do you mean: For example, on Tricky 1 (this should be a doddle) build, don't stop the lemmings by any means (since they will turn around and they'd be going left and the exit is to the right so they're screwed) and then force-bash through the stone?

--on the big challenge--How is Just Dig possible with 1 digger and nobody hitting the left wall? I don't see how (1) digger can dig a hole with lots of lemmings and they don't turn around.

[Proxima]

That's more or less it. On Tricky 1 and similar levels, you just have to ensure that (1) everyone is always heading to the right, so crowd containment is prohibited; (2) anyone who does turn left dies before they can turn right again. However, there are a couple of loopholes arising from the exact wording of the challenge. One is that it's okay to take a path that involves lemmings going past the exit, turning, and approaching it from the right. Another is that individual lemmings can turn, perform actions that are necessary to create a path for the crowd, and then die -- Taxing 28 is an example where this is necessary.

[ccexplore]

--on the big challenge--How is Just Dig possible with 1 digger and nobody hitting the left wall? I don't see how (1) digger can dig a hole with lots of lemmings and they don't turn around.

That was a different challenge that doesn't follow the rules of the current challenge exactly.  In particular the left wall of the digger pit doesn't count for that older variant.

[ccexplore]

Fun 12 confirmed possible.  My solution for DOS Lemmings loses 30 of the 80 (the minimum is 50% = 40/80).  It is highly likely that similar solution works in other versions as well (and even better %-saved for versions with 100 instead of 80 lemmings).  Lemmix replay attached.  (If you want to verify the "no turn" part, you can edit the level in Lemmix so that there's no left wall at the pit right of the wall, and then run the replay, so that it becomes clear whether anyone turned around or not at the pit.)

Will update post later with more verbal description of solution, but it's glitch-free and not too hard to guess really.

[Clam]

Contrary to the note in the first post, here's Fun 14 100%. The key is to use the climbers and floaters to spread out the crowd, reducing the need for multi-bashing.

Fun 15 is pretty easy using the 'sadistic' route (send turned lemmings to their death), just send a climber over, mine through the floor and let the next 40 lemmings die.

edit: Added Fun 17 100%.

[Clam]

Tricky 3, 4 and 5 improved to 100%. There seems to be an emerging theme here of crazy bridges... (at which point I remember two-thirds of L1 is building so this is to be expected )

[ccexplore]

Fun 22 confirmed.  My solution for DOS Lemmings saves 64/80, the minimum required.  You can of course lose 4 more on versions with 100 lemmings.  %-wise I'm sure there's room for improvement, though I don't know about 100%.

Hard to say anything for sure about the Mac version due to the hi-res graphics, but it is at least plausible.

[Proxima]

Hard to say anything for sure about the Mac version due to the hi-res graphics, but it is at least plausible.

Unfortunately I won't be able to test as the "special" levels don't work on my Lemmings -- the background colour acts as solid terrain!

Fun 15: I wasn't aware it's one of the levels with a different save requirement on different versions. Should have realised, as that "nuke" challenge in the big thread makes it obvious.

[ccexplore]

My Taxing 16 solution for the "assign to right-facing lemmings only" challenge satisfies the criteria of this challenge as well.  It's non-100% and uses steel glitches, namely bombing down the steel drop by exploding away the steel.  You can get the replay from the linked post; I've attached a screenshot here for convenience.

One critical factor of whether it works in other versions or not is how the builders behave towards the top boundary of the screen.  It should stop but without turning around.  Bombing away the steel is likely to work in a number of versions including Mac, though it hasn't been tested on this level.  Recall that here, you have to be falling slightly away from the edge to be able to bomb it.

[LemSteven]

Tricky 9 and 11 are now confirmed.  9 obviously uses the right route.  One lemming does the bridge work to get to the top of the steel, and I used a bit of steel glitching to get the bridge started in a favorable vertical position.  The next 19 or so lemmings are all climbers.  One of them completes the path to the exit, while all of the others do a bunch of mining through the obstacle at the lower right so as to delay them.  I ended up getting 94% (71/75), but more is certainly possible.  100% may even be doable.

For Tricky 11, the first 20 lemmings are climbers.  The first climber bombs and then the second can clear the path to the exit.  One of the others can then turn around and then repeatedly dig+mine such that a stairway is made for the crowd.  He finishes up right around the time that the 21st lemming enters the level.

I haven't had any luck on Tricky 10, but I suspect it may be possible with an insane amount of multitasking/delaying.  Unfortunately, the release rate, having two entrances, and the amount of building required really work against you.

EDIT: Also confirmed Tricky 20, Tricky 28, and Tricky 29.  Tricky 29 is good for 100%.

[Clam]

Tricky 9 and 11 are now confirmed.  9 obviously uses the right route. [...] 100% may even be doable.

Indeed it is.

Going back to the first post again, Mayhem 25 is possible, and in fact made fairly easy by the fact you can use interrupted basher and miner strokes to get up to the exit. This means sacrificing two lemmings of course, so no chance of getting 100% this way.
edit: Improved to 100%! (by a different method)

Also a couple more (relatively) easy ones, Fun 19 and 21 with 100%.

[ccexplore]

Here's Fun 16 100%.  Unfortunately it uses blockers (Yes, blockers for a no-turn challenge, and it really is no-turn, not even "turn once after getting past exit".  Just watch the replay) in a probably crucial way, so it doesn't help for Taxing 3.

My execution uses some DOS-specific features, such as the missing lava, and that diggers tend to last a little longer in DOS because they stop digging if they remove absolutely nothing on their stroke.  I don't think they are critical, but they unarguably increase the odds of success slightly.  I do believe I can at least tweak my solution to have a few more spare builders for delay uses, so it's still plausible in other versions I think.  And there might be better approaches too I suspect.

[LemSteven]

I've added Taxing 2, Taxing 5, and Taxing 9 to the list of confirmed results.  Taxing 9 is good for 100%, as required.

Also, since Clam Spammer confirmed Mayhem 25 100%, I'd assume that Tricky 13 would be 100% as well.

[Clam]

Tricky 28 and Taxing 2 improved to 100%, both replays attached.

Taxing 18 is possible using the bash-beneath-the-wall route, you need to bomb out the left side (or even simply bomb every lemming that turns) so no lemmings turn around twice.

Taxing 20 is easily done with 100%, you just have to

climb, dig and bash at the start.

Taxing 25 gives you just enough skills to stall enough lemmings by bashing through the floor.

Taxing 27 is pretty much just the regular solution, minus the crowd control.