I played Havoc 3 and discovered something. I think in the DOS version a basher is sometimes able to stroke past two walls if you bash in the right place. The NeoLemmix Mechanics cuts that glitch out. Anyway, I discovered three methods.
First (and that I think is the intended solution, saving a climber and a floater AFAIK) is to bash the three pipes, and let one lemming turn back to do the hard work while the other lemmings explore the landscape. The big bubble wall must be mined, but let the worker lemming climb a bit to gain a bit of height before doing so. He can therefore build once the breakthrough is made so that he can mine the wall he just climbed. As you need 100% IMO holding the others back like this is a unique method, and uses the full landscape fantastically well. I see that trick is repeated into Havoc 13 on the TLE (Not sure if we're keeping this or not). I think that's a backroute, as the intended solution is to build over the big rocky wall, mining near the end of it, before bashing the next.
Another method on Havoc 3 that TLE discovered was to force your way into the terrain pit, building into it, possibly keeping a few lemmings at bay with climbers, but bashing one the stair is made and enough height is gained. Trapping lemmings like that is also quite a unique concept.
The third is to just mine and build the last pipe with the second lemming, and bash the bubble wall with the first like most players would. I think that's unintentional, as it abuses the terrain of the starting platform, but we can't really do anything about that for now.
So, given the unique trapping method in what I think is the intended solution, I say we should keep this level.