Left hatch: We dig immediately when we've walked past the steel. The digger will cluster some lixes from the left hatch in his tunnel.
The digger is frame-perfect; the desired effect is that, once the digger breaks through the bottom, at least one lix faces backwards, i.e., leftwards. No other digger placement will produce any lix facing backwards.
After digger's breakthrough, implode one of the right-facing fallers to make a hole at half height into the left wall.
Float and climb the left-facing faller, he'll climb into the hole, make him build a splatform for the crowd from the right hatch.
Saves 5/10, exactly the save requirement.
I've watched
Proxima's replay to check whether Proxima also digs near the left wall, but Proxima doesn't dig here. I haven't watched Proxima's replay further, to not be spoiled.
