Game logic

How the fuck do they code games so that everything moves smoothly and at a consistent rate regardless of the speed of the machine you run it on, and still have tons of shit interacting with each other somehow?
Maybe I need to find a good open-source candidate to have a look at.

Also, I wish I knew the correct terms to describe what I'm talking about.

>>23
Yes, that's true. However most of these include physics and more importantly serve as examples of complete engines which handle the problem in OP. It's funny that the physics engines you list are used by engines I have deliberately omitted.