gistfile1.js

cursores = game.input.keyboard.createCursorKeys();

if(cursores.left.isDown) {
    lastDirection = 'left';
    uno.scale.x = -1;
    uno.body.velocity.x = -1*velocity;
    uno.animations.play('right'); //uno.scale.x=-1 hace que right se voltee a left
} else if (cursores.right.isDown) {
    lastDirection = 'right';
    uno.scale.x = 1;
    uno.body.velocity.x = 1*velocity;
    uno.animations.play('right');
} else {
    uno.body.velocity.x = 0;
    uno.animations.play('stand_' + lastDirection);
}