I've come up with a once-per-rank level now. The concept behind this one is the same basic layout, but some of the exact details change between each version of it - for example, in one of them there's an extra wall, in another one the one-way field points in the opposite direction. All versions have the same lemming count, and a 100% save requirement. The time limit gets exponentially less each time (with the 4th iteration setting a new Lemmings Plus record for lowest time limit), while the release rate increases linearly. The number of skills reduces each time from 10 of each, to 5, then 3, then 1; in all four cases you've got four different skills, but
which skills varies between iterations. (As awesome as the idea of the skillsets all being mutually exclusive is - and that could work since there's 16 skills to choose from - I didn't go with this in the end. So some skills appear in more than one iteration, although there is no skill that appears in all four iterations.)
And, I also decided to give the once-per-rank level its own unique music. In a way Lemmings Plus II did this as well, but in that case it was more a side effect of that the once-per-rank level was a Frenzy level, and no other levels were; this time it's been done fully intentionally.
By the way - still no final decisions as to the last graphic set, so feel free to throw more ideas at me.
Preferably those that'd work well for a semi-rough-edged graphic set (think similar to the Snow, Tree or Martian styles, in terms of roughness - not to the level of roughness that Rock, Purple or Sky would be).
Poll