Compiling How to add new sprites? (weapons, monsters, items?) Do i need custom client?

[blue lamb]

I'm trying to make an OT based off of another game.
I want it to have items and monsters from Mario. I want to know this info before reading tutorials and stuff so I know its possible.

Will other people be able to join my server if I make a monster that looked like a creature from Mario?

 

[JoSePh15_]

It is possible, u will need a custom client yes.