Like tears... in... rain.
Key Rule Changes
Experience = Gold
Experience comes solely from treasure. A small treasure hoard (as per the DMG) is an easy encounter’s worth of XP. A medium hoard, a medium encounter. And so on.
You do have to get the treasure back into town, however, for it to count.
Variant Rules in Play
Pretty much all of them.
In particular, Variant Human Traits (PHB page 31), Equipment Sizes (PHB page 144), all of Chapter 6 in the PHB, Encumbrance (PHB page 176), Playing on a Grid (PHB page 192).