[yoklov]

I don't think "simple and use a single set of rules" describes the control code for any shipping (action) game. At least none I've worked on. They're all complex piles of special cases and hacks in an effort to make the movement 'feel' right (which works, but is disheartening at first, until you start to expect it).

[striking]

The Sonic Physics Guide is how I implemented my first (good) platformer physics.

https://info.sonicretro.org/Sonic_Physics_Guide

It's fairly hack free in the abstract. But reality is often a little different, based on the quirks of your collision detection.