Awesome work!
Do you want to allow users use assets or code of your game? If not, you don't need to change anything...
License is about permissions of user. What user can/can't do with the work. https://en.wikipedia.org/wiki/License
Each license describes different permissions and "behaves" different.
website i recommend about choosing a license: https://choosealicense.com/
Fully support this! This is so helpful! I actually was just learning about metadata this week in my photography class and how you can set it in adobe light-room. I had no idea itch.io supported it too!!! I have been making digital art for years and literally just learned what metadata is... (yep I'm slow haha!) thank you so much for sharing this! It is really important and helpful for fellow creators.