Yes it's a scam.
As you said sweetmes other games are giving updates for free more regularly on what are called "public version".
I will never spend one buck on momoiro software anymore.
A shame.
Yeah sorry, I don't frequently post dev updates on twitter, i mostly just make sure I do monthly updates.
A lot of recent dev has been documentation and optimization for new content. As a result there's not much to show or talk about as far as what works on twitter. Because of this, I wrote a long post a couple weeks ago to explain.
Hopefully this gives perspective.