I suppose something like may have been done before somewhere... but I've certainly never seen anything like it. It works very well, both because it permits precise maneuvering that would not be possible any other way, and because it introduces a real tension as you watch the color of your health bar turn blue. This, of course, is thematic in an abstract way: the colder you get, the less able you are to exert yourself, climb high, jump down safely, etc.
The hazards are quite varied (spikes, pits, 2 kinds of enemy). Those birds really gave me a run for my money.
Although the graphics are brought together from different sources, they work pretty well together.
There are some missed opportunities in terms of sound design. Trudging through the snow was a bit too loud. Both picking up the wood and depositing it are key events, and should be emphasized with sound effects.