Neutral lemmings are an interesting idea, had never thought of that! So I guess they would behave sort of like the "green pants-blue hair"-lemmings in 2 Player-mode do when there's no second player around to control them? Minus pickup skills, of course; in a 2 player game, those would be given to the player who controls the lemming picking up the skill, instead of the single player who leads a neutral lemming to picking up a skill.
Putting in my two cents, I think it makes sense that zombies should trigger traps and buttons by walking into them, but not so much pickup skills, as zombies are considered "enemies" and thus should not give you skills they run into, but them walking on buttons should not be any different than normal lemmings doing so.
Yeah, that was kind of where I was coming from, too
. I had only considered pickup skills and exits as a bonus option, but the reason I even considered suggesting a change regarding the behaviour of zombies was their inability to push buttons.
If we think about it from a flavour standpoint, it would actually make more sense for zombies to trigger buttons (by passively walking onto them) through their weight, but not being able to disarm traps. Instead, I have a level now where you have to use zombie disarmers to disable traps, but none where they need to push buttons ^^.
Anyway, we're arguing from a flavour or "realism" standpoint here; IchoTolot's argument is the "game mechanical" one, since he strives for consistency across all Neo Lemmix expansions, and I understand it would be a huge pain to have to rework all existing zombie levels (I'd have to do the same for mine, too) if we wanted to retroactively apply these changes to all packs.
However, with the pool of packs constantly expanding, I don't know how realistic this consistency approach can last in the long term. My brother is currently playing Oh No! More Lemmings in Neo Lemmix, and that pack for example still has timed bombers (because without them, e.g. the very last level "Look before you leap" would be totally broken). So there are already inconsistencies between packs. In Lemmings Revolution, you can use a bomber as a floater by giving the lemming something else to do before it blows up - then it stops being a bomber again. Also, you can use blockers as "terrain" because other lemmings land on their heads rather than just falling through them like in other games.
Hence, just as bombers switch between timed and instant between packs, I could imagine a similar setup for zombies. Consistency within a pack should still be strived for, so that the players know what set of rules they are dealing with.
Anyways, neutral lemmings as proposed for Lix certainly would be a good place to start. That would allow to experiment on completely new ground without touching the old stuff, and then, if the new element is appreciated, one could reconsider whether the option - not mandatory change for everyone - would be worth enabling for zombies as well.
Speaking of Lix: Would be pretty fun to smack the zombies around with that baseball bat, wouldn't it?
One way you can make use of zombies somewhat in this fashion is by using a setup similar to what Apocalypse 1 of Doomsday Lemmings does.
That's precisely how I changed that "zombie button presser level" then as a consequence: Making them run into one-use traps so the real lemmings are safe. Funnily enough, these mine traps look very similar to the exit unlock buttons from the metal tileset ^^, so they had the side effect of confusing the player a little.