Nice Idea for a puzzle game. The core concept was intuitive to figure out, but I were still sometimes a bit confused about what exactly to do.
I really liked the approach for the tutorial to tell someone, when they did something wrong instead of letting them read a long text beforehand. Found that much more enjoyable, because the information was relevant to me.
I think a few small changes in the presentation could help for understanding:The top bar isn't really consistently used. In some levels it shows the sum of all numbers on the floor and in others it shows the sum of all highlighted fields.
The first time I saw the bar I also thought the objective was to stay lower then shown number.
I think the highlighted fields could have stood out more then the fields you already visited and I think the visited field should have some sort of barrier, so its obvious you can never go on that fiel again
In my opinion the levels about highlighted fields were most enjoyable. I think I mostly try and error-ed the others, but not being able to cross you own paths made figuring out a path for reaching the fields correctly really fun. But maybe combining the two objectives would be even better