Because I am a dope of the highest order of magnitude, I forgot to talk about one of the most important features I have planned for 0.13.0: a seasonal cycle. I plan to have the average temperature and fertility automatically fluctuate over the course of one hour simulation time (by default).
Of course, from the creatures perspective this will be less like seasons and more like glacial cycles, due to their short lifespans and rapid evolution. I’m okay with that. Creatures will be forced to continually adapt to survive, rather than simply reaching a local maxima and stagnating.
The season-cycle graph will be present on the Map Editor screen, and it will be editable, with the ability to set the magnitude, length and offset of both the temperature and fertility curves with simple click-n-drag handles. By including a separate curve for both Temperature and Fertility, the game will have a maximum of 4 distinct seasons: hot, cold, wet and dry, depending on which curve is closest to a peak at any given moment.
Long term, I plan to associate each season with in-game visual and weather effects. This might not make it into 0.13.0, though: I consider it a nice-to-have, not a priority.