Well, Christmas is cancelled this year I guess :(

Not necessarily. If they insist on there being only 12 puzzles, all they need to Save Christmas is to start the event on Christmas day, and rename it to "12 Puzzles of Christmas" or "Advent of Three Kings of Code", or such -- see: https://news.ycombinator.com/item?id=45710963.

They could also publish the puzzles only every second day, I guess.

That was my first thought too, and I'd prefer it, cause sometimes I'll get stuck on a problem, or I'm busy, or I forget, and I'd rather have one more day. Bur it's Eric's call in the end.

Give a kid half of an advent calendar and tell them to open the window every second day, let's see how long it'll keep their interest (I expect much less than 12 days) :). That's not how Advent Calendars work!

We’re not kids though…

Let your hair down man, it's christmas!

Or publish the harder version of the puzzle on a different day to the easier version.