Technically, it’s quite polished (using the mouse and WASD would be more convenient than the arrow keys). However, it lacks a bit of visual clarity. You should consider using less harsh colors with more contrast — personally, I had a hard time seeing the blue balloons against the blue background.
I would’ve liked to know how far along I was in the game, because I played for almost 10 minutes and never saw the boss that’s supposed to show up around the 6-minute mark. I died several times, but I couldn’t tell if I was restarting from the beginning or from where I left off, since the XP/balloon bar stayed the same.
Keep it up!