TRI is a promising first person puzzle platformer where you create 3D triangles that act as platforms which allow you to walk on walls etc.
“TRI will be a first-person 3D game with environmental puzzles. It is inspired by great games like “Portal”, “Thief” and “Zelda”. The main gameplay: You create triangles to build platforms, overcome obstacles, walk on walls, reflect light rays and lasers, and more. It is still work in progress, and even substantial parts of the gameplay and design might change in the near future.”