Bah humbug.
OK, I owe you one for that, so here are all known solutions to It's Hero Time:
(1) First lemmings is an athlete. Last lemming digs platform, bashes OWW, builds over water. Athlete mines to exit.
(2) First lemming digs platform then bashes into OWW so that one lemming goes past. He builds over water. One lemming is an athlete and mines to exit.
(3) First lemming mines platform then bashes into OWW so that one lemming goes past. He digs down OWW such that the basher enters his digging before he breaks through, the basher stops and heads left. Digger then builds over trap trigger.
(4) Similar, but bash into OWW so that no lemmings go past; basher then becomes digger.
(5) First lemming mines platform. Block on top of OWW so that one lemmings goes past. He digs right edge of OWW. Last lemming bashes to release blocker; these two enter dig pit and, because of the sloping ground, are released to the left. Digger builds over trap trigger.
(6) Third-last lemming digs platform so two lemmings go down. One bashes into OWW then builds over water; the other is turned round and mines to exit.
(7) First lemming mines platform then blocks on slope of OWW. Last lemming bashes to release blocker (he will be turned round by bash tunnel) then digs and builds over trap trigger.
A couple of these solutions have to be done slightly differently in different versions of the game.