The idea is very simple and most likely is on github, but I can’t find it.
Bitcoin address generator based on 12 phrases (address;private key) and checking the address from the list of all addresses (addresses.txt) when matching addresses are found, writing them to the file found.txt (address;private key)
Maybe someone met a similar implementation?
I guess that your point is searching for a collision / attempt of steal some coins.
One reason for such tools' scarcity would be that they are expected to be useless: there are far too many addresses that can be generated, hence all you'll do is to waste energy.
Another reason for the scarcity is that they may be seen pretty much as illegal.
However, @BitMaxz pointed out some tools. Maybe you'd elaborate what's all this about and maybe somebody can tell you whether it worth the effort or not.
PS. From what I know, both "Bitcoin challenge" and "Bitcoin alpha" (last one probably scam) are not related to HD wallets.