Here's my fix: http://jsfiddle.net/jlas/CT2pG/1/ http://jsfiddle.net/jlas/CT2pG/1/ Easy one line fix for this: need to check if new dx / dy is opposite the old

Here's my fix: http://jsfiddle.net/jlas/CT2pG/1/ http://jsfiddle.net/jlas/CT2pG/1/ Easy one line fix for this: need to check if new dx / dy is opposite the old dx / dy and use the old one if so. var _dx = (e.keyCode - 38) % 2, _dy = (e.keyCode - 39) % 2; dx = (_dx*-1 === dx) ? dx : _dx, dy = (_dy*-1 === dy) ? dy : _dy; I also added another fix to disallow moving twice during one cycle.