Hi. I had two options:
- Inverted. Feels like you are controlling the neighboor piece. If you press down, the top piece go down, if you press left the left piece go right, and go on.
- Normal. You control the empty piece. If you press up, the empty piece go up, if you press down, the empty piece go down, and go on.
I tried the two approachs, the 'Normal' approach was better on my opinion. Maybe the inverse option would be nice with swipe controls, you swipe right to move left piece to right, instead move empty piece to right.