Which should I work on first?

Botaniki has been a project of mine for a long time, but at the point I am now, I am not sure where to take it. There are many aspects that need replacement, enhancement, and even fixing. I don't know where to start.

So I will leave it up to you, as the player to tell me which part of the game you want me to work on first.

Shall I work on the UI and menus first? Perhaps add more levels, or more things within the levels first? What do you think needs immediate attention.