make sure to visit their twitter and Facebook pages, (the arrow at the top of the map). You get 2 stars for it and you only have to visit the page. (no facebook or twitter account needed!)
Great game. Certainly makes you put in the minutes, but it doesn't have the same gritty arcade feel of the others (not surprising considering its a christmas game)
 "Kingdom Rush"){kind=icon}
 "Boxhead the Christmas Nightmare"){kind=icon}
 "Gun Mayhem"){kind=icon}
 "Backyard Monsters (removed)"){kind=icon}
 "The Adventures of Red"){kind=icon}
 "Massive Mayhem 3"){kind=icon}