What follows is probably something that has been thought of and written about by others and if so it should be deleted unless it spurs interesting comments anyway.

But in case it hasn't, I thought I'd mention my recent realization that all chess moves are in one of six categories. Sort of like how I had a similar realization that I could write an article about limit poker called The Eight Mistakes In Poker which I did thirty five years ago (no limit adds the ninth mistake of betting the incorrect amount).

I'm not a chess player but that doesn't change the fact that all chess moves are one of six possible types. Call them S1, S2, S3, S4, S5, or S6, named after me of course if I am somehow the first to have thought of them.

All moves are of exactly one of these types. But it is rare that even great non computer players will know which category to put them in. On the other hand I'm hoping that attempting to characterize chess moves using those six categories might be an interesting addition to chess analysis.

An S1 move is one where there exists a forced checkmate for you and your move doesn't change that.

S2 is a move where you had a forced checkmate but have turned it into a forced draw (given perfect play of course).

S3 is a move that turns your forced checkmate into a forced checkmate against you.

S4 is a move that preserves your forced draw.

S5 is a move that changes your forced draw situation into a forced loss.

S6 is a move where you are facing a forced loss so it obviously can't change anything.

I believe all first moves are S4. Maybe black's reply could be S5 as well as S4 but I don't know.

Obviously these situations are talked about all the time using full sentences. But just maybe my categories have not been explicitly coined as I have just done. Without that it is harder to talk about questions like "what percentage of Magnus Carlson's moves are in each category?" Or to throw out an insult like "nice S3".

Man, I've been waiting years to be able to throw out "nice S3" instead of "you just played yourself." I will surely be the most stylin' hustler in the park.

I'm not really sure there is...any...utility in these categorizations. Until you get down to 7 pieces, there are tons of positions that aren't "forced" anything. We could make an educated guess but who knows.

E.g. First moves are S4? I mean...probably, maybe? But I don't know if/when it can ever be proven. And if it can't, it's not really "forced," is it? You can add the word "probable" in front of "forced" to cover all the massive amounts of grey areas but now the categories have even less utility (maybe negative utility?)

Sorry if I come off sounding harsh. I must be missing something because I can't think of a situation where these categories are helpful. One thing that may be helpful to note, is that determining S2-S3 needs to be done via engine or post-game analysis (otherwise, you are not making those moves in the game). As such, those categories seem purely theoretical anyway and it can be very misleading to think of two S2 moves as part of the same category (of course they are, but not in a helpful way in terms of improving at actually playing chess).

Most games are won or lost and abandoned long before checkmate, so checkmate is actually pretty irrelevant unless you are down a lot of material.

Draws in the opening are not forced, you´d have to use the term "equal position", but equal positions between humans are not necessarily drawn, especially not if there is a difference in ability.

And one can´t even raise today´s strongest computer evaluations to gospel. About ten years back Rybka 3 was considered the holy allmighty and it subsequently got destroyed by Houdini and then came Komodo etc. and then came Stockfish which was wiped out by AlphaZero. Stockfish 12 is state of the art today, but it will look meaningless in two years.

It's probably true, but it's impossible to prove without a massive computer that doesn’t exist yet. And the comments would be speculation without one, (except in clear positions, with strong chessplayers making the comments).

I believe both Black and White can play S5 moves (e.g. 1.f3 e5 2.g4?? [S5 unless it already happened on move 1] Qh4#)— but I agree that first moves are mostly S4 with a bunch of S5 thrown in, commonly called blunders.

So Korchnoi's 39. Ra1?? against Karpov would be classified as S5 because it loses to checkmate in 3 starting with 39...Nf3+!!

Usually players tend to resign long before checkmate if it becomes inevitable.
Or if they're about to lose because of irreversible material loss.