It would be great if Trees that grow in snowy biomes are their Snowy Variants!
Same saplings, but just checks to see whether it's biome is snowy or not, right?

So, for a number of reasons, I'm not going to do this.

Basically, in order to properly replace tree placement I have two options:

1. Only replace vanilla trees, by manually re-implenting each and every tree feature to use snowy blocks.

• This is something I don't even do right now - the snowy trees you see in primal winter were done using a cheeky hack, which replaces the blocks while the chunk is generating, and importantly only during chunks present in world generation.
• This is much more reliable than trying to modify the vanilla tree features, especially once you factor in modded trees which could be using vanilla leaves.
• So, not feasible, due to the possible downsides and the maintenance effort of replacing all vanilla tree generation.

2. Use the same hack I do for world gen, but for all worlds.

• This is a non-zero performance cost, and a very invasive hack if I extend it past just world gen chunks, to all chunks.
• This wouldn't just replace trees - it would replace every block. Even if the user placed it by hand, or placed it outside of a snowy biome. This is quite clearly not viable, as if I wanted to do that, I would've registry-replaced the vanilla blocks themselves.

In addition to the technical reasons, I don't think this is particularly a good idea. Trees don't grow snowy, they get snowy by the accumulation of snow on top of them. Which is something I think I could do, although it would be less comprehensive, by exploiting the same way snow currently grows. But not simply replacing the trees themselves. To that effect I've opened #42, which is likely where I would take this feature.