#LDJAM Parallel Shift is a game that allows you to solve basic level puzzles by shape shifting. There are collectibles and dangers along the way however, in the end it's pretty basic. You can shift between a square, line, a big square and a circle. All have their own benefits.
On Ludum Dare: http://ludumdare.com/compo/ludum-dare-35/?action=preview&uid=71704