Download the FFIX conversion mod here.

1.0 - Base mod uploaded
1.1 - Fixed an error in the entity file
1.2 - Added about half of the new creatures, did some rebalancing in small areas
1.3 - Moar monsters, some bug-fixing, trying out new things
1.4 - More bug-fixing a few new things
1.5 - Fixed stuff, lots of new stuff!
1.6 - Fixed the frostbite issue
1.7 - Fixed sawmill, added some small things
1.8 - Fixed that fucking worldgen crash, did some things
2.0 - New big version, includes new magic system, many spells, beginnings of elemental system and new reactions and metals
2.1 - New buildings and reactions, some more balancing and minor fixes
2.2 - New magic research system, some bugfixes, went total conversion for this download

Installation instructions:
Extract into a custom folder. Run game and enjoy.