For December 2013, I did an Advent calendar, posting one level a day until Christmas. These are those levels, compiled into three downloads. Since the filesize of all of the levels together exceeds 15,000 KB, I couldn't do a single download.

Also included is something special: When I posted a screenshot of the base interior of Frozen in Time, RDs.Empire asked if he could make his own level out of it. I said sure, and the finished product lies within.

The levels:
December 16: Gravitational Exchange
December 17: Hazardous Obstacle Course
December 18: Essentia Velocitas
December 19: Balance or Fall
December 20: Aqua Tube
December 21: Ski Jumping
December 22 and 23: Final Obstacle Course (Warning: VERY long and difficult; I would recommend skipping this one.)
December 24: Christmas Tree
December 25: Frozen in Time
Special: Winter Wonderland Hunt, by RDs.Empire