This sounds promising. I am happy to see the idea of RPG Maker MMOs isn't dead yet. However I have a few questions.
You write about auth, chat and movement sync. What other MMO related features does your plugin have?
Also unfortunately I have to bring to you that CAPTCHA Mechanisms are not ment for DDoS Protection. They don't make ddos attacks any harder at all.
I would also be very happy if you could elaborate on the communication layer.