Update 3 is here. Make sure to reload the page to see the effects.
Fixed an issue where newly-spawned resources weren't immediately clickable.
Adjusted the cursor position so it better matches where you're actually clicking.
Claudius does not like being hit with snow and ice, and will enrage upon being damaged (though he'll probably calm down when the event is over).
Reduced the cost of castle and log cabin pieces.
Icing and gumdrops can now be placed on top of walls.
Wreaths can now be placed on walls.
Chess squares can now be placed under objects.
The "Build" action on most items has been replaced with "Build Another," letting you quickly duplicate items.
Added extended versions (three tiles long) of the Castle and Short Ice walls.
Also going to consolidate previous posts here to avoid too many recommended posts.
Update 4 (reload the event to see):
Gaining XP after level 50 now continues to fill your XP bar. You'll get two random presents full of resources every time you fill it. If you've already been gaining XP at max level, you'll find a bunch of presents already waiting for you.
The helpful text box during battle has gotten shy from all the attention and now runs away from your mouse.
The Peace on Earth is finished refueling and is now ready to spread holiday cheer to all of your enemies.
The Trojan Reindeer is now ready to roll into battle.
Damaged weapons can again be used as long as their HP is above zero.
Hovering over a disabled weapon will explain why you can't use it.
You can now unlock (free) upgrades to your base at certain levels. Replace your tent with a nice cozy igloo, log cabin, or finish off your castle with a keep. Upgrading also updates the look of the inside of your base.
The castle gate piece can now be rotated. If you feel like having the sunrise in your face as you leave your castle every morning, now you can.
The issue of the misnamed "corner path" piece has been straightened out.
A new magical statue is available (at level 50) under the "Special" category. This statue allows you to repair items in a 4x4 area for reduced cost (once per hour).