i think what made it possible was really good planning and on-the-spot rescheduling. we also cut about a 5th of the world map halfway through the jam and worked right up until the deadline. iirc the worldmap was done saturday evening and we essentially placed all the content on the map during the last 12 hours of the jam!
Yup like Stasys said, we cut away a big chunk that was going to be a combination of the last biome mixed with another biome based on a different crystal design!
Originally, the top of the map was also connected to Boneblight, but scrapping the 5th biome actually allowed for a more controlled, linear experience that was way easier to manage in such a short time.