Ahh I dont know how I managed that! Played again last night in Chrome and it was much better, music and sounds and no space between the tiles.
For what it is I think you have done a pretty good job, if I had to nitpick I would maybe suggest being able to move backwards after jumping (though you might have it there for balance reasons). It might have also been cool if you could deflect the enemy lazers with your sword instead of having to avoid them everytime.
Good job and look forward to seeing the next project :)