I disagree. Plants are my immediate area of concern, but animals should be differentiable into cold/balanced/subtropical as well.

I also don't think it's a given that it would be easier to implement a completely new kind of tag, which would require new handling in worldgen, than it would be to expand an already-existant system.

They would both be a fair bit of work, but adding 'sub-biomes' is just adding more detail to an existing system while adding temperature tokens to plants is a new system. Biomes are determined by drainage and rainfall. Somewhere with both high rainfall and drainage is a forest. This wouldn't change at all. The 'sub-biome' is then determined by temperature(in turn determined by altitude and latitude); At one end of the scale you have really cold forests being taigas and at the other really hot tropical forests with temperate forests in between. This would be being made more granular.


Creatures and plants that currently appear in temperate sub-biomes would need to be gone through to decide which also appear in the cold temperate and subtropical sub-biomes.

I must admit that giving plants more detailed requirements, temperature included, is something I'd like. It would allow some plants to grow in areas they are not native to. Like in real life the rich may import compatible seeds and use the plants to display wealth. Some plants may even grow better in a non native setting and become invasive.

They would both be a fair bit of work, but adding 'sub-biomes' is just adding more detail to an existing system while adding temperature tokens to plants is a new system. Biomes are determined by drainage and rainfall. Somewhere with both high rainfall and drainage is a forest. This wouldn't change at all. The 'sub-biome' is then determined by temperature(in turn determined by altitude and latitude); At one end of the scale you have really cold forests being taigas and at the other really hot tropical forests with temperate forests in between. This would be being made more granular.

Biomes already have a temperature seperate from what kind of biome they are.  The plants are just using this.

The range of the plants or creatures could be declared by the rainfall, drainage, temperature, altitude, savagery and evil without regard for what the biome is called.  They're all just numbers, and the rainfall/drainage/savagery/evil ones are conveniently scaled 0 to 100.  So is a score called vegetation, though that seems more like an output of plant placement than an input.  Temperature is also in a familiar scale.  Altitude might be an issue because I'm not sure what the baseline is, and if it is comparable across worlds.

For backward compatibility the biome tags can be used as shortcuts.

When and if weather gets more realistic, things other than temperature can change with the seasons.  For example, subsurface frost might depress the drainage score well into Spring, or water drained from upstream is added to "rainfall" to get seasonal floodplains.