Monster Flavour - It's Halloween so Death Cobs get replaced with Angry Jack-o-Lanterns with no mechanical change just sprite and description. It's winter, ice-themed monsters are more common, etc.
It implements an independently developed permabuff system. It restores the removed High Elf and Mountain Dwarf species and adds a new Faerie Dragon species intended to be a straightforward option for spellcasting. It's autumn, most the trees are in their autumn sprite style (leaves changed, etc.) Stoat Soup was started because of dissatisfaction with the removal of monster spawns over time in 0.21 it restores these spawns. It's Halloween so rations may use a candy apple sprite and a message about eating candy on eating most the plants are pumpkins and some have been carved into jack-o-lanterns.
Visual/flavour - It's Spring so a lot of the plants in the lair are blooming.
Which kinds of changes would you be alright with for Seasons and Holidays? Holidays may partially overwrite seasons IE: White Christmas (Snowing) even though it's Summer (Southern Hemisphere). Setting it to a particular holiday will make the game act as if that holiday when it's not setting to week would use the holiday about two weeks around the holiday (default) setting to day uses that day none will force no changes even when it is the holiday. Holiday - (any supported holiday, like say Halloween or Christmas)/week/day/none Probably default to Southern (to match that it's originally an Australian game) unless set. None would ignore the system to be current behavior. Northern or Southern gets the current season for that Hemisphere. Setting it to a particular season forces that season regardless of the time of year. Season - spring/summer/autumn/winter/northern/southern/none I'm thinking about adding Season and Holiday changes to my fork though I'm not sure if I'll do much on it before Halloween it is Halloween that's got me thinking about it and I'll use FALL and HALLOWEEN as examples here.