I really like this. I love seeing Bitsy games that subvert the system to act like a different kind of UI. Moving the cursor around is perfect, and the interaction with apps and messages feels great. The grey palette worked really well. Loved the power button to end the game, too.
I read the messages from bottom to top, but I got the impression they were meant to be read from top to bottom. You could maybe nudge players to do it that way by warping the cursor to the top.
The messages were a little hard to read all smushed together. It takes a lot of effort, but you could carefully insert {br} line breaks if you wanted to clean up the way they show in the dialogue boxes.