Thanks! All assets (music/pixel art) were not done by me (they are linked on the page). Otherwise I am using a godot template that has already all my settings configured like screen size, import settings, fonts and so on.
It also helped to plan everything ahead of time. I like to make a todo list that is ordered to know exactly what to do next. (For example the things I couldn't include because I pushed them down on the todo-list were a custom death screen or a timer)