Seasons Clock
solsword

API for getting various "season" parameters based on server time and a few customiable settings. Doesn't change gameplay; just a library that other mods can use to do seasonal things.

anarchy
solsword

Anarchy PCG library (see https://cs.wellesley.edu/~pmwh/anarchy/lua/ w/ docs at https://cs.wellesley.edu/~pmwh/anarchy/lua/docs32/index.html)