Rodrigo Monteiro’s “Guide to Implementing 2D Platformers”
I’m a sucker for grids, and diagrams, and other such things, but this article by Rodrigo Monteiro is a true gem of a breakdown on the different approaches one can take to a 2D platformer even without the pretty pictures. He not only goes through the base mechanics of each of four implementation styles (“pure” and “smooth” tile-based, bitmasked and vector, if you’re curious), but also the inevitable oddities such as slopes, ladders, and one-way and moving platforms, and some more general topics such as character acceleration and jumping.
It doesn’t actually throw much in the way of code at you, and what is there is very well-explained, so this an excellent a primer as I’ve ever seen, even if you’re not a budding programmer. If you are, though, it’s a bit of a must.
(Thanks to Rick Gilliland for the tip-off and programming stamp of approval.)