It's too bad that the game doesn't allow making a lemming a builder if it overlaps with another builder. That's why I had to add the floaters.
Not sure why you think that.
There are at least 2 ways the game allows this to happen:
1) The game automatically tries the skill assignment on a walker (more or less) if it is also highlighting a lemming already performing a skill, but that lemming cannot take on the new skill assignment. In particular, if you have a walker overlapping with a builder, you will be able to assign the walker builder.
2) You can also explicitly ask the game to perform the skill assignment on a walker (more or less), in place of a lemming currently performing a skill (as per usual prioritization), by holding down the right mouse button while clicking with the left. For example, say you have a walker overlapping with a digger, and you are trying to assign builder. The game would normally assign the builder to the digger, but if you hold down the right mouse button, have the cursor highlight both lemmings, and click with the left button, the game will instead pick the walker to be assigned builder.
Moreover, unless the 2 lemmings are truly in the exact same position, you can usually carefully position the mouse cursor to only highlight one or the other.
Anyway, all the above should work in Lemmix and the various DOS Lemmings. I don't know about Lemmini, but you shouldn't be using that for this challenge game anyway since it's based on the DOS game mechanics and not Lemmini's.
So perhaps it is possible after all to modify your level to work with my challenge?
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I might try to clean that level up for a levelpack. Seems like it'd be a bit hard to not make the solution obvious, though
True to a point. The reason I brought up that point is because this challenge is inspired by a somewhat notorious series of levels made by namida with the keyword "Oblivion" in the level names. It is similar to the concept behind this challenge game, except in namida's versions, it works horizontally instead of vertically. In both cases, it's fair to argue that given the unavoidably uneven skill distribution, it probably won't take too long for the player to realize what must be done. On the other hand, it might still at least present some initial difficulties for very casual Lemmings players, who are more used to using one or two blockers to block off the rest of the crowd, instead of using nearly 1 blocker for every lemming. (And to be fair to namida, in his versions at least it is more plausible for the player to attempt solutions that do not use so many blockers, so it's slightly less obvious what must be done.)
And my main point is that your level is more of a "real levelpack" kind of level than mine, which is even more stripped down, to the point where it would really seem a little silly (or at least more silly) to be included in an actual levelpack.