Gravity Revision was a game I did at University. The goal was to create a 3D PC game without any graphics engine in order to learn how to work with graphics cards. Gravity Revision is a puzzle game and the solution to each level lies in flipping a levels orientation (i.e. changing the gravity vector) into any of 6 orientations (the sides of a cube). Because I was curious I also decided to create my own physics engine. Since this turned out to be quite a bit more difficult than I initially imagined. It took up quite a lot of my resources and I almost didn't finish the game in time.
At first the player can't change gravity at will and is confined to jumping on buttons. Later on he will aquire the Higgs Gun which can shoot beams of highly concentrated Higgs at the walls surrounding the level. Walls which can be targeted are colourful while others are grey-ish. Once a wall has been hit by the beam it will emit Higgs particles and everything that is affected by gravity will fall in that direction.
You can download the game here. I will upload and post the code once I have found it on one of my old machines.
Each level is concluded by a giant glowing cube which not only serves the function of finalising each level, it also provided three of the necessary graphics features I needed to pass the course ;)