L, this is outstanding. The layout is perfect, and considered. I hope you will expand this with more levels. My first score was -71:( Looking forward to trying again (-11 this time)

And I love the mac-ish black and white tiles, by the way.

Oh! one thing that may be an error: when on the stairs I triggered a tile to go red diagonally through another tile--I'll try to repeat and get a picture. Okay, it seems to only be an issue with this one staircase, but my testing was not particularly rigorous.

Here.

Here.