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.

>>2
If the game is running on delta-time at one frame every two seconds wouldn't the physics differ from a computer running one frame every one second? Say the velocity is recalculated every cycle of the game loop based on acceleration- if fps = 2.0, this is calculated twice as often as fps = 1.0- resulting in a desync between the two machines even if the input is identical.