Question on desing contest

Can the idea be taken from a popular show or series?

Dont think so, can be flagged for copyright

As long as it doesn’t look completely identical

Synthwave Helmet for example is a Daft Punk reference

Claymore is also a reference weapon

Say you want to make a Final Fantasy 7 reference and create Sephiroth’s One-Wing.

It could look somewhat similar as long as it doesn’t copy the design. Then again I doubt they’ll be adding such a wide sprite.