I've been retheming a lot, but keep getting tempted by all the contests popping up on BoardGameGeek. Many are a bit too restrictive for my tastes (9 cards?!) while others are for games for which I don't need more (2 player wargames, hm). Then the One Page contest came out. You can do whatever components you'd like, as long as they fit on the front side of one page of standard paper.
My game is presently called Arctic Dash, a race for narwhals beneath the ice flow. You speed beneath the ice, building your track as you go. If the leader forges ahead, you build as you keep in front, or your pod in the back can sense the way with their horns, slowing your way with seaweed.
It's turning out pretty playable.