Well, if you remember the last 4 grades of primary school, you'll be alright.
Basically, it's whatever you wanted to know and we kept it a secret... until now.
This Blender tutorial teaches you how to make a Heads up display that will display your score. It will also show you how to make it so that that score increases when you collect a certain object.
A quick tutorial on Object Constraints used with the physics engine. We should really have called it "Rigid Body Joints". Which is the type of Object Constraint we are demonstrating.