Hey Santi! Great job getting value out of the one button. The ability to move in both directions works really well, and creates some strategic depth as you need to figure out which direction to go in, and whether its one or two presses to go that way.
To nitpick a bit on this topic, I think it might be nice if when going straight down, the arrow gives some sort of indication as to what direction it will move it next. I would occasionally forget (because I have the memory of a goldfish apparently), and I think it would just be a nice polish/QoL change.
That's pretty nitpick-y and not a super necessary thing to address though, and I really want to double down on how much I love your use of movement tied to the one button. Very clever.