What is a write up and diagram? PLease help!

Hi,

Can someone tell me what this person means by

“I want you to design a puzzle using the mechanics established in a 2D video game. This ideally would be a write up and basic diagrams.”

Any help will be really appreciated! I need to do this

Sounds like they want a design document. If you Google it you should see quite a few examples. I would clarify with them exactly how big and detailed they want it though.