People who code! Or want to code!
https://adventofcode.com has started!
25 days of two coding puzzles unlocking each day, which you can do in any language (people have even used bash/Excel/etc). Varying difficulty and you don’t have to complete the previous to do the next day.
Each year has a story about saving Christmas. One year you had to break into the Easter Bunny HQ. This year apparently involves time travel.
Do AoC! My friend/coworker runs it but even if he didn’t I’d say that.