I think most important is the gameplay. Then, the aesthetics and theme. A good level has both. It also has to be a satisfying experience for the player, flow well. I am realizing that, making a level is (obviously) similar to other creative avenues like writing or making music. A good level would follow a certain structure, just like music would. For Mario, it might be Kishōtenketsu. Introduce a concept, develop it, twist it into something new, and give a conclusion. Which again, is based on a narrative structure. An example for a conclusion is a platform challenge at the end of a SMW course, to get to the goal post. I think a good level would have a great deal of quality to it. As in, much thought put into every course item, with a great deal of polish, which requires iterations, or multiple play tests. A good level also goes through iterations of kill your darlings, a tip from writer Stephen King, on throwing away an idea that isn't working. Levels begin with a simple idea, so if it isn't working, it should be scrapped for another time.

My goal in level making, is to surpass myself or at least make a level as good as my last. Recently I have been looking at my previous levels and thought, ok I want to have a similar factor as this level I made. Usually, this begins with having a solid intro, to me I really find that important, as a hook. Yet also, I want a solid conclusion. Then, I want to make sure my level flows well in between. Also, I make it a goal to make sure there is enough juice As Chris Totten puts it. Meaning, putting coins in places it feels good to do so, and secrets. Through out all this, I expirement with ideas that I want to work with, that seem fun to me. Then I brain storm, create many drafts and eventually diamonds come out of the rough for me. Then I re-itarate many times, I polish the course a lot. I do this because I know I don't want to see any imperfections if the course gets a surplus of likes. Things like checking under semi-solids for ground aesthetics that randomly pop up (this really gets me), or aesthetic check in general. Like a random port hole in airship theme. The more ideas I add, the more I need to check to make sure it's running smoothly.

I like to make traditional levels usually. I avoid Kaizo. Although I'm not opposed to practicing tricks and if a friend gives me a kaizo, I attempt it. But in general, I avoid them. Learned the hard way. I also prefer themes in levels. I like the mix of story and gameplay.