meaning - Easy is to beginner as medium is to

I want to display three levels in my game...but I don't know what the text should say.

easy -> Beginner

medium -> ?

hard -> Expert

Basically, I want the form that describes the person playing the game, instead of the game itself. What adjective is best?

I have considered adept.

I doubt my users will know what adept means. Also, I need something in between expert and beginner. Adept falls into the expert category. Is there anything more common that I can use, that has the same impact as the other two words I mentioned?

Proficient would work, theoretically, but in day-to-day term, the levels "beginner - proficient - expert" won't sound great.