The official Mighty No. 9 Twitter account revealed today that the demo is now live on Humble Bundle, as well as the new release date for the title:
Hey Mighties! We have two big announcements for you! The MN9 Demo is LIVE on Humble Bundle. And we have a new release date!
— Mighty No. 9 (@MightyNo9) September 25, 2015
According to the Kickstarter page, the new release date for North America is February 9th, 2016 and February 12th, 2016 for the rest of the world.
The Kickstarter update also states that most of the issues with the online modes have been fixed by both Deep Silver and Inti Creates.