Simple no-CPU-impact, full-page snowflakes, gently falling and swaying in the soft wind.
Light-blue-ish.
Install, and they are on for everyone, until you toggle the plugin off in the ACP or uninstall.
If you want all the configurations made available to you and maybe let users toggle it on/off on the front end, make with the hew and cry and I'll grab a beer and code it out but that one will cost you a few bucks (once).
Not mine, I'm just packaging it up for INVCOM 4x. MIT licensed: https://github.com/hcodes/snowflakes