I'd spam their Twitter and Facebook telling people not to buy their stuff and remind people they screwed you out of a game. Maybe that will force an answer from them. Sometimes a PR nightmare is needed.
Hucast is essentially just one guy, and it looks like he's effectively done with development anyway. He hasn't had good PR for some time, and doesn't seem to care about it.
I was one of the first to preorder 'Ghost Blade,' and once it came out that entire modes were missing, I asked for a refund and did get it. Now, that was years ago, but that's why I still hope people can get refunds on 'Redux 2' preorders if they ask,
I truly feel for the people who gave pre-order money.
However, I am not sad to see Hucast games go TBH. They were part of what's a bit wrong with physical indie game products (not just on Dreamcast.) The constant re-releases, different overpriced editions of the same games, and of course Ghost Blade being released incomplete.
We have more devs entering the scene these days, so I am hopeful they won't repeat the same mistakes.