screen moves too much when moving the player.

fun game, looks great too.
but the arrow keys to move also moves the browser window. if that can be fixed, it needs to be done asap.

additions to consider:
a title screen, a proper countdown to the start of the game, point counter, various things to collect that are worth more points but are there for a shorter amount of time, incremental difficulty increase to a cap so it doesn't become actually impossible. maybe mines could spawn along with the boxes for extra challenge and something else to avoid.

this is great work for your first game, keep at it