BFBB Winter Wonderland is a fun simple mod that originally started off as a mod titled "BFBB Christmas Edition." It's goal to simply give BFBB a winter time aesthetic (with a few exceptions), while throwing in a few gimmicks for every level. The mod also has a custom soundtrack! Track list is provided in the readme.
Get the mod here!
This google drive folder contains a download for the mod, and a Steamgrid folder in case you wish to add the mod to your Steam Library.
It also contains a readme file that is highly recommended to be read.
Disclaimer: It is highly recommended that you create a backup of your BFBB iso. Just in case something in the mod installation process goes wrong.
Check this video out if you want to build the mod as a rom https://www.youtube.com/watch?v=uK5HI6fQVK4
Alternatively, you can use this method here. Setting up Dolphin for Modding This method is recommended if you are a modder or play a lot of mods.