I've just finished my first 2D project on Unity and decided to try my hand at 3D. I'll start with the prototyping new mechanics and then I'll see what can be made of this.
Today I've made a standard control for 3D first-person games: A-W-S-D to move and spacebar to jump. The camera is moved with the mouse and then you can move forward. The rotation of the camera along the X axis is limited so that you can't rotate it through a full 360° and watch behind your back. A perfect example is the first-person mode in Skyrim.