What distinguishes “early”, “mid” and “end” games?

Recently William_S posted:

In my mental model, we’re still in the mid-game, not yet in the end-game.

I replied:

A thing I’ve been thinking about lately is “what does it mean to shift from the early-to-mid-to-late game”.

In strategy board games, there’s an explicit shift from “early game, it’s worth spending the effort to build a longterm engine. At some point, you want to start spending your resources on victory points.” And a lens I’m thinking through is “how long does it keep making sense to invest in infrastructure, and what else might one do?”

I assume this is a pretty different lens than what you meant to be thinking about right now but I’m kinda curious for whatever-your-own model was of what it means to be in the mid vs late game.

He replied:

Like, in Chess you start off with a state where many pieces can’t move in the early game, in the middle game many pieces are in play moving around and trading, then in the end game it’s only a few pieces, you know what the goal is, roughly how things will play out.

In AI it’s like only a handful of players, then ChatGPT/​GPT-4 came out and now everyone is rushing to get in (my mark of the start of the mid-game), but over time probably many players will become irrelevant or fold as the table stakes (training costs) get too high.

In my head the end-game is when the AIs themselves start becoming real players.

This was interesting because yeah, that totally is a different strategic frame for “what’s an early, midgame and endgame?”, and that suggests there’s more strategic frames that might be relevant.

I’m interested in this in the context of AI, but, also in other contexts.

So, prompt for discussion:

a) what are some types of games or other “toy scenarios,” or some ways of looking at those games, that have other strategic lenses that help you decisionmake?

b) what are some situations in real life, other than “AI takeoff”, where the early/​mid/​late game metaphor seems useful?