Guide Rudolph (or other creatures!) to the presents using the arrow keys. When you get more points other things appear. Can you find the hidden cheat that lets you go through walls. (Ok, this is a bug. But it's quite cool.) Click on 'see inside' to find out how it works. Can you change the number of points awarded? add more presents? Add things to avoid that lose you points?
Special cheat: press x to hide dragons (when you get to them!), d to bring them back. I've found some very young children are scared of them and you might want to remove them.