Hey thanks for giving my prototype a try!
And that's a very interesting comment! I actually did not change the arrow key controls at all after I implemented touch controls! And originally the left and right keys correspond to x-1 and x+1. You start at x0.y0 and end at xN.yN...
To make it match the touch controls, two keys should be pressed instead of one. I'm not sure that is better. Or I could move away completely from arrow or wasd controls but then that another bit of text that would need to go up, and I would like to keep text to a minimum...
A fuller game would allow for configurable keys. That would be the most correct thing to do I think.