The game looks really good,
The pixel art is really well done.
On another hand, the game mechanics can be abused pretty easily, I just ended up pressing space every time the bar was too much to the left or too much to the right. It would of been nice to force the player a little more to switch between mammoth and foot. Maybe also put boulders you can't run into or something to force the player to move left and right.
Otherwise the game is really good looking and feels pretty nice to play even if it can be abused pretty easily :)