Unearthed Arcana: 3-way XP

[Wilb]

Here it goes!

EDIT: it is very simplified and helps with campaigns that do not intend to drown the world in blood. It is almost a halfway between normal XP and milestone, but simple enough that it can be implemented with no bumps.

[Nytemare3701]

I like it. It does the job XP is designed to do (create a virtual reward to track incremental progress between levels) without the pitfalls normally associated (arbitrary XP values attached to monsters for example)

[Nifft]

Combat
You gain XP for defeating monsters in combat, whether by slaying them or leaving them in a state in which they pose no threat. (...)
The XP you gain for defeating a monster is determined by comparing the monster’s challenge rating to your level.

Oh hey 3e Encounter Level mechanics, long time no see.

[Agita]

I don't know how I feel about the specific execution, but the fundamental idea of it should really have been in the DMG. Even better would be a guideline for letting GMs pick their own conditions for XP game tailored to the theme and goals of their game. These are a decent default for the "typical" D&D game, but given they acknowledge your game might not hew exactly to the three pillars they push, it would be nice of them to also explicitly acknowledge the possibility of tweaking these.
Incidentally, the combat section still entirely ignores the possibility of bypassing combat encounters without necessarily defeating them, such as by stealth or trickery.

I do like it better than the methods of milestone advancement or even "level up when the GM says so" that I often see expounded, even by the developers themselves.

[Wilb]

I don't know how I feel about the specific execution, but the fundamental idea of it should really have been in the DMG. Even better would be a guideline for letting GMs pick their own conditions for XP game tailored to the theme and goals of their game. These are a decent default for the "typical" D&D game, but given they acknowledge your game might not hew exactly to the three pillars they push, it would be nice of them to also explicitly acknowledge the possibility of tweaking these.
Incidentally, the combat section still entirely ignores the possibility of bypassing combat encounters without necessarily defeating them, such as by stealth or trickery.

I do like it better than the methods of milestone advancement or even "level up when the GM says so" that I often see expounded, even by the developers themselves.

I agree with your post, and a DM may stretch this

Combat
You gain XP for defeating monsters in combat, whether by slaying them or leaving them in a state in which they pose no threat. (...)
The XP you gain for defeating a monster is determined by comparing the monster’s challenge rating to your level.

Oh hey 3e Encounter Level mechanics, long time no see.

to allow bypassing encounters but still getting to whatever was beyond that as "defeating" the enemies, considering the streamlining of values and stretching of acquisition methods are thorough enough to keep the suspension of disbelief if rewards are given for such acts.

[awaken_D_M_golem]

tangent for/from Wilb
http://storm-shelter.minmaxforum.com/index.php?topic=102.msg2760#msg2760

... ENWorld usually gets a tweet over fastest on these things.  But then I lose them.
http://www.sageadvice.eu/2017/06/21/are-there-psionics-in-xanathars-guide/

But they indicate elsewhere (some UA-ish neighbor) that they'll do a Psi setting book
and it "might" be in there whenever wherever.