Stardew valley 100 days rules?

[Megamaster X Tiktok]

What are the rules of a Stardew valley 100 days and is online multi-player allowed?

 

[ShneekeyTheLost]

Depends on how you want to do it, really. Set your own rules.

I know '100 days' has become something of a meme, but given that ends mid-winter, you may as well call it a Year 1 Challenge.