Custom Lemmings is somewhat dead, though it still works. However, it appears that the other games are better to use mechanic-wise, since those are the mechanics most of us are used to. Otherwise what looks like a dangerous fall will be safe, and let's say there's one floater and a few builders. Don't ask what the floater is for, but the player might use builders they were supposed to use elsewhere! Of course, you'd have to question why they would be running those CustLemm physics, but that's a different topic...