I would choose the first one. Especally as last exam or something, you can show what ideas you have in mind. Creativity is important in game design so this is the one to go with.

A fan project might be a bit easier to develope, but you have to reach others fans attention with this game. Usually people like what they have, they don't like changes. So if you create a fan project, it might happen that people will dislike it without even playing it cause it's "just" a copy.

Choose the first one, limit your levels, chars, ideas, etc to your conditions, implement your own ideas and creativity and show your potential in the world of game design.

Good luck with it!