This variant goes one step beyond a Magic Point or Spell Point system to link those points to physical things: mithril, and it's various manifestations. In this magic variant spellcasters have to gather supplies with which to power their spells, whether that means purchasing them, slowly distilling their fuel from the environment, theft, or foraging. 

This variant results in less powerful spellcasters with limited resources, and slows the pace of play. It's most suitable for a game that's using slower rests (e.g., a 'short rest' takes place overnight, a 'long rest' requires a week or a campsite).

For many adventuring parties being knocked unconscious is a penalty only if you actually miss your turn. There are so many healing abilities that spending more than a round at 0 hp is often a long-forgotten memory after 4th or 5th level when healing word and revivify become de rigueur choices for your bard, druid, cleric, and celestial soul sorcerer. 

This can keep combat quick and smooth, but also has the disappointing effect, noted at gaming tables worldwide, of making combat a kind of nothing event in most cases. If there's no consequence beyond using a 2nd-level spell slot for being reduced to 0 hp, why try to avoid it? 

The answer in this case is to reintroduce consequences for reaching 0 hp without crippling a character. There are several ways to do this, three of which are presented here.

Social combat is an expanded set of rules for social interactions. Instead of making a single check to represent getting your way in a conversation, you’ll take a number of steps that resemble a complex skill check.

A story-focused game that starts as if it were at the far end of a run of Lasers & Feelings: characters can do anything a superhero can do with no problem, but struggle with any check relating to everyday life.

Super, and human.